1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 2007-2008,2010 7 * Swinburne University of Technology, Melbourne, Australia. 8 * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org> 9 * Copyright (c) 2010 The FreeBSD Foundation 10 * Copyright (c) 2010-2011 Juniper Networks, Inc. 11 * All rights reserved. 12 * 13 * Portions of this software were developed at the Centre for Advanced Internet 14 * Architectures, Swinburne University of Technology, by Lawrence Stewart, 15 * James Healy and David Hayes, made possible in part by a grant from the Cisco 16 * University Research Program Fund at Community Foundation Silicon Valley. 17 * 18 * Portions of this software were developed at the Centre for Advanced 19 * Internet Architectures, Swinburne University of Technology, Melbourne, 20 * Australia by David Hayes under sponsorship from the FreeBSD Foundation. 21 * 22 * Portions of this software were developed by Robert N. M. Watson under 23 * contract to Juniper Networks, Inc. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 3. Neither the name of the University nor the names of its contributors 34 * may be used to endorse or promote products derived from this software 35 * without specific prior written permission. 36 * 37 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 38 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 40 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 41 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 42 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 43 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 45 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 46 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 47 * SUCH DAMAGE. 48 * 49 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 50 */ 51 52 #include <sys/cdefs.h> 53 #include "opt_inet.h" 54 #include "opt_inet6.h" 55 #include "opt_ipsec.h" 56 #include "opt_rss.h" 57 58 #include <sys/param.h> 59 #include <sys/arb.h> 60 #include <sys/kernel.h> 61 #ifdef TCP_HHOOK 62 #include <sys/hhook.h> 63 #endif 64 #include <sys/malloc.h> 65 #include <sys/mbuf.h> 66 #include <sys/proc.h> /* for proc0 declaration */ 67 #include <sys/protosw.h> 68 #include <sys/qmath.h> 69 #include <sys/sdt.h> 70 #include <sys/signalvar.h> 71 #include <sys/socket.h> 72 #include <sys/socketvar.h> 73 #include <sys/sysctl.h> 74 #include <sys/syslog.h> 75 #include <sys/systm.h> 76 #include <sys/stats.h> 77 78 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 79 80 #include <vm/uma.h> 81 82 #include <net/if.h> 83 #include <net/if_var.h> 84 #include <net/route.h> 85 #include <net/rss_config.h> 86 #include <net/vnet.h> 87 88 #define TCPSTATES /* for logging */ 89 90 #include <netinet/in.h> 91 #include <netinet/in_kdtrace.h> 92 #include <netinet/in_pcb.h> 93 #include <netinet/in_rss.h> 94 #include <netinet/in_systm.h> 95 #include <netinet/ip.h> 96 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 97 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 98 #include <netinet/ip_var.h> 99 #include <netinet/ip_options.h> 100 #include <netinet/ip6.h> 101 #include <netinet/icmp6.h> 102 #include <netinet6/in6_pcb.h> 103 #include <netinet6/in6_rss.h> 104 #include <netinet6/in6_var.h> 105 #include <netinet6/ip6_var.h> 106 #include <netinet6/nd6.h> 107 #include <netinet/tcp.h> 108 #include <netinet/tcp_fsm.h> 109 #include <netinet/tcp_seq.h> 110 #include <netinet/tcp_timer.h> 111 #include <netinet/tcp_var.h> 112 #include <netinet/tcp_log_buf.h> 113 #include <netinet6/tcp6_var.h> 114 #include <netinet/tcpip.h> 115 #include <netinet/cc/cc.h> 116 #include <netinet/tcp_fastopen.h> 117 #ifdef TCPPCAP 118 #include <netinet/tcp_pcap.h> 119 #endif 120 #include <netinet/tcp_syncache.h> 121 #ifdef TCP_OFFLOAD 122 #include <netinet/tcp_offload.h> 123 #endif 124 #include <netinet/tcp_ecn.h> 125 #include <netinet/udp.h> 126 127 #include <netipsec/ipsec_support.h> 128 129 #include <machine/in_cksum.h> 130 131 #include <security/mac/mac_framework.h> 132 133 const int tcprexmtthresh = 3; 134 135 VNET_DEFINE(int, tcp_log_in_vain) = 0; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(tcp_log_in_vain), 0, 138 "Log all incoming TCP segments to closed ports"); 139 140 VNET_DEFINE(int, blackhole) = 0; 141 #define V_blackhole VNET(blackhole) 142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 143 &VNET_NAME(blackhole), 0, 144 "Do not send RST on segments to closed ports"); 145 146 VNET_DEFINE(bool, blackhole_local) = false; 147 #define V_blackhole_local VNET(blackhole_local) 148 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 149 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 150 "Enforce net.inet.tcp.blackhole for locally originated packets"); 151 152 VNET_DEFINE(int, tcp_delack_enabled) = 1; 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 154 &VNET_NAME(tcp_delack_enabled), 0, 155 "Delay ACK to try and piggyback it onto a data packet"); 156 157 VNET_DEFINE(int, drop_synfin) = 0; 158 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 159 &VNET_NAME(drop_synfin), 0, 160 "Drop TCP packets with SYN+FIN set"); 161 162 VNET_DEFINE(int, tcp_do_prr_conservative) = 0; 163 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr_conservative, CTLFLAG_VNET | CTLFLAG_RW, 164 &VNET_NAME(tcp_do_prr_conservative), 0, 165 "Do conservative Proportional Rate Reduction"); 166 167 VNET_DEFINE(int, tcp_do_prr) = 1; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 169 &VNET_NAME(tcp_do_prr), 1, 170 "Enable Proportional Rate Reduction per RFC 6937"); 171 172 VNET_DEFINE(int, tcp_do_lrd) = 0; 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_lrd, CTLFLAG_VNET | CTLFLAG_RW, 174 &VNET_NAME(tcp_do_lrd), 1, 175 "Perform Lost Retransmission Detection"); 176 177 VNET_DEFINE(int, tcp_do_newcwv) = 0; 178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 179 &VNET_NAME(tcp_do_newcwv), 0, 180 "Enable New Congestion Window Validation per RFC7661"); 181 182 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 183 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 184 &VNET_NAME(tcp_do_rfc3042), 0, 185 "Enable RFC 3042 (Limited Transmit)"); 186 187 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 189 &VNET_NAME(tcp_do_rfc3390), 0, 190 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 191 192 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 193 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 194 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 195 "Slow-start flight size (initial congestion window) in number of segments"); 196 197 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 199 &VNET_NAME(tcp_do_rfc3465), 0, 200 "Enable RFC 3465 (Appropriate Byte Counting)"); 201 202 VNET_DEFINE(int, tcp_abc_l_var) = 2; 203 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 204 &VNET_NAME(tcp_abc_l_var), 2, 205 "Cap the max cwnd increment during slow-start to this number of segments"); 206 207 VNET_DEFINE(int, tcp_insecure_syn) = 0; 208 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 209 &VNET_NAME(tcp_insecure_syn), 0, 210 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 211 212 VNET_DEFINE(int, tcp_insecure_rst) = 0; 213 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 214 &VNET_NAME(tcp_insecure_rst), 0, 215 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 216 217 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 218 #define V_tcp_recvspace VNET(tcp_recvspace) 219 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 220 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 221 222 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 223 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 224 &VNET_NAME(tcp_do_autorcvbuf), 0, 225 "Enable automatic receive buffer sizing"); 226 227 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 228 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 229 &VNET_NAME(tcp_autorcvbuf_max), 0, 230 "Max size of automatic receive buffer"); 231 232 VNET_DEFINE(struct inpcbinfo, tcbinfo); 233 234 /* 235 * TCP statistics are stored in an array of counter(9)s, which size matches 236 * size of struct tcpstat. TCP running connection count is a regular array. 237 */ 238 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 239 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 240 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 241 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 242 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 243 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 244 "TCP connection counts by TCP state"); 245 246 /* 247 * Kernel module interface for updating tcpstat. The first argument is an index 248 * into tcpstat treated as an array. 249 */ 250 void 251 kmod_tcpstat_add(int statnum, int val) 252 { 253 254 counter_u64_add(VNET(tcpstat)[statnum], val); 255 } 256 257 /* 258 * Make sure that we only start a SACK loss recovery when 259 * receiving a duplicate ACK with a SACK block, and also 260 * complete SACK loss recovery in case the other end 261 * reneges. 262 */ 263 static bool inline 264 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 265 { 266 return ((tp->t_flags & TF_SACK_PERMIT) && 267 ((to->to_flags & TOF_SACK) || 268 (!TAILQ_EMPTY(&tp->snd_holes)))); 269 } 270 271 #ifdef TCP_HHOOK 272 /* 273 * Wrapper for the TCP established input helper hook. 274 */ 275 void 276 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 277 { 278 struct tcp_hhook_data hhook_data; 279 280 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 281 hhook_data.tp = tp; 282 hhook_data.th = th; 283 hhook_data.to = to; 284 285 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 286 &tp->t_osd); 287 } 288 } 289 #endif 290 291 /* 292 * CC wrapper hook functions 293 */ 294 void 295 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 296 uint16_t type) 297 { 298 #ifdef STATS 299 int32_t gput; 300 #endif 301 302 INP_WLOCK_ASSERT(tptoinpcb(tp)); 303 304 tp->t_ccv.nsegs = nsegs; 305 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 306 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 307 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 308 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 309 tp->t_ccv.flags |= CCF_CWND_LIMITED; 310 else 311 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 312 313 if (type == CC_ACK) { 314 #ifdef STATS 315 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 316 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 317 if (!IN_RECOVERY(tp->t_flags)) 318 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 319 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 320 if ((tp->t_flags & TF_GPUTINPROG) && 321 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 322 /* 323 * Compute goodput in bits per millisecond. 324 */ 325 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 326 max(1, tcp_ts_getticks() - tp->gput_ts); 327 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 328 gput); 329 /* 330 * XXXLAS: This is a temporary hack, and should be 331 * chained off VOI_TCP_GPUT when stats(9) grows an API 332 * to deal with chained VOIs. 333 */ 334 if (tp->t_stats_gput_prev > 0) 335 stats_voi_update_abs_s32(tp->t_stats, 336 VOI_TCP_GPUT_ND, 337 ((gput - tp->t_stats_gput_prev) * 100) / 338 tp->t_stats_gput_prev); 339 tp->t_flags &= ~TF_GPUTINPROG; 340 tp->t_stats_gput_prev = gput; 341 } 342 #endif /* STATS */ 343 if (tp->snd_cwnd > tp->snd_ssthresh) { 344 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 345 if (tp->t_bytes_acked >= tp->snd_cwnd) { 346 tp->t_bytes_acked -= tp->snd_cwnd; 347 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 348 } 349 } else { 350 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 351 tp->t_bytes_acked = 0; 352 } 353 } 354 355 if (CC_ALGO(tp)->ack_received != NULL) { 356 /* XXXLAS: Find a way to live without this */ 357 tp->t_ccv.curack = th->th_ack; 358 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 359 } 360 #ifdef STATS 361 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 362 #endif 363 } 364 365 void 366 cc_conn_init(struct tcpcb *tp) 367 { 368 struct hc_metrics_lite metrics; 369 struct inpcb *inp = tptoinpcb(tp); 370 u_int maxseg; 371 int rtt; 372 373 INP_WLOCK_ASSERT(inp); 374 375 tcp_hc_get(&inp->inp_inc, &metrics); 376 maxseg = tcp_maxseg(tp); 377 378 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 379 tp->t_srtt = rtt; 380 TCPSTAT_INC(tcps_usedrtt); 381 if (metrics.rmx_rttvar) { 382 tp->t_rttvar = metrics.rmx_rttvar; 383 TCPSTAT_INC(tcps_usedrttvar); 384 } else { 385 /* default variation is +- 1 rtt */ 386 tp->t_rttvar = 387 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 388 } 389 TCPT_RANGESET(tp->t_rxtcur, 390 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 391 tp->t_rttmin, TCPTV_REXMTMAX); 392 } 393 if (metrics.rmx_ssthresh) { 394 /* 395 * There's some sort of gateway or interface 396 * buffer limit on the path. Use this to set 397 * the slow start threshold, but set the 398 * threshold to no less than 2*mss. 399 */ 400 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 401 TCPSTAT_INC(tcps_usedssthresh); 402 } 403 404 /* 405 * Set the initial slow-start flight size. 406 * 407 * If a SYN or SYN/ACK was lost and retransmitted, we have to 408 * reduce the initial CWND to one segment as congestion is likely 409 * requiring us to be cautious. 410 */ 411 if (tp->snd_cwnd == 1) 412 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 413 else 414 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 415 416 if (CC_ALGO(tp)->conn_init != NULL) 417 CC_ALGO(tp)->conn_init(&tp->t_ccv); 418 } 419 420 void inline 421 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 422 { 423 INP_WLOCK_ASSERT(tptoinpcb(tp)); 424 425 #ifdef STATS 426 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 427 #endif 428 429 switch(type) { 430 case CC_NDUPACK: 431 if (!IN_FASTRECOVERY(tp->t_flags)) { 432 tp->snd_recover = tp->snd_max; 433 if (tp->t_flags2 & TF2_ECN_PERMIT) 434 tp->t_flags2 |= TF2_ECN_SND_CWR; 435 } 436 break; 437 case CC_ECN: 438 if (!IN_CONGRECOVERY(tp->t_flags) || 439 /* 440 * Allow ECN reaction on ACK to CWR, if 441 * that data segment was also CE marked. 442 */ 443 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 444 EXIT_CONGRECOVERY(tp->t_flags); 445 TCPSTAT_INC(tcps_ecn_rcwnd); 446 tp->snd_recover = tp->snd_max + 1; 447 if (tp->t_flags2 & TF2_ECN_PERMIT) 448 tp->t_flags2 |= TF2_ECN_SND_CWR; 449 } 450 break; 451 case CC_RTO: 452 tp->t_dupacks = 0; 453 tp->t_bytes_acked = 0; 454 EXIT_RECOVERY(tp->t_flags); 455 if (tp->t_flags2 & TF2_ECN_PERMIT) 456 tp->t_flags2 |= TF2_ECN_SND_CWR; 457 break; 458 case CC_RTO_ERR: 459 TCPSTAT_INC(tcps_sndrexmitbad); 460 /* RTO was unnecessary, so reset everything. */ 461 tp->snd_cwnd = tp->snd_cwnd_prev; 462 tp->snd_ssthresh = tp->snd_ssthresh_prev; 463 tp->snd_recover = tp->snd_recover_prev; 464 if (tp->t_flags & TF_WASFRECOVERY) 465 ENTER_FASTRECOVERY(tp->t_flags); 466 if (tp->t_flags & TF_WASCRECOVERY) 467 ENTER_CONGRECOVERY(tp->t_flags); 468 tp->snd_nxt = tp->snd_max; 469 tp->t_flags &= ~TF_PREVVALID; 470 tp->t_badrxtwin = 0; 471 break; 472 } 473 474 if (CC_ALGO(tp)->cong_signal != NULL) { 475 if (th != NULL) 476 tp->t_ccv.curack = th->th_ack; 477 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 478 } 479 } 480 481 void inline 482 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 483 { 484 INP_WLOCK_ASSERT(tptoinpcb(tp)); 485 486 /* XXXLAS: KASSERT that we're in recovery? */ 487 488 if (CC_ALGO(tp)->post_recovery != NULL) { 489 tp->t_ccv.curack = th->th_ack; 490 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 491 } 492 /* XXXLAS: EXIT_RECOVERY ? */ 493 tp->t_bytes_acked = 0; 494 tp->sackhint.delivered_data = 0; 495 tp->sackhint.prr_out = 0; 496 } 497 498 /* 499 * Indicate whether this ack should be delayed. We can delay the ack if 500 * following conditions are met: 501 * - There is no delayed ack timer in progress. 502 * - Our last ack wasn't a 0-sized window. We never want to delay 503 * the ack that opens up a 0-sized window. 504 * - LRO wasn't used for this segment. We make sure by checking that the 505 * segment size is not larger than the MSS. 506 */ 507 #define DELAY_ACK(tp, tlen) \ 508 ((!tcp_timer_active(tp, TT_DELACK) && \ 509 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 510 (tlen <= tp->t_maxseg) && \ 511 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 512 513 void inline 514 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 515 { 516 INP_WLOCK_ASSERT(tptoinpcb(tp)); 517 518 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 519 switch (iptos & IPTOS_ECN_MASK) { 520 case IPTOS_ECN_CE: 521 tp->t_ccv.flags |= CCF_IPHDR_CE; 522 break; 523 case IPTOS_ECN_ECT0: 524 /* FALLTHROUGH */ 525 case IPTOS_ECN_ECT1: 526 /* FALLTHROUGH */ 527 case IPTOS_ECN_NOTECT: 528 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 529 break; 530 } 531 532 if (flags & TH_CWR) 533 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 534 else 535 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 536 537 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 538 539 if (tp->t_ccv.flags & CCF_ACKNOW) { 540 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 541 tp->t_flags |= TF_ACKNOW; 542 } 543 } 544 } 545 546 void inline 547 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 548 { 549 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 550 } 551 552 /* 553 * TCP input handling is split into multiple parts: 554 * tcp6_input is a thin wrapper around tcp_input for the extended 555 * ip6_protox[] call format in ip6_input 556 * tcp_input handles primary segment validation, inpcb lookup and 557 * SYN processing on listen sockets 558 * tcp_do_segment processes the ACK and text of the segment for 559 * establishing, established and closing connections 560 */ 561 #ifdef INET6 562 int 563 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 564 { 565 struct mbuf *m; 566 struct in6_ifaddr *ia6; 567 struct ip6_hdr *ip6; 568 569 m = *mp; 570 if (m->m_len < *offp + sizeof(struct tcphdr)) { 571 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 572 if (m == NULL) { 573 *mp = m; 574 TCPSTAT_INC(tcps_rcvshort); 575 return (IPPROTO_DONE); 576 } 577 } 578 579 /* 580 * draft-itojun-ipv6-tcp-to-anycast 581 * better place to put this in? 582 */ 583 ip6 = mtod(m, struct ip6_hdr *); 584 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 585 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 586 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 587 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 588 *mp = NULL; 589 return (IPPROTO_DONE); 590 } 591 592 *mp = m; 593 return (tcp_input_with_port(mp, offp, proto, port)); 594 } 595 596 int 597 tcp6_input(struct mbuf **mp, int *offp, int proto) 598 { 599 600 return(tcp6_input_with_port(mp, offp, proto, 0)); 601 } 602 #endif /* INET6 */ 603 604 int 605 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 606 { 607 struct mbuf *m = *mp; 608 struct tcphdr *th = NULL; 609 struct ip *ip = NULL; 610 struct inpcb *inp = NULL; 611 struct tcpcb *tp = NULL; 612 struct socket *so = NULL; 613 u_char *optp = NULL; 614 int off0; 615 int optlen = 0; 616 #ifdef INET 617 int len; 618 uint8_t ipttl; 619 #endif 620 int tlen = 0, off; 621 int drop_hdrlen; 622 int thflags; 623 int rstreason = 0; /* For badport_bandlim accounting purposes */ 624 int lookupflag; 625 uint8_t iptos; 626 struct m_tag *fwd_tag = NULL; 627 #ifdef INET6 628 struct ip6_hdr *ip6 = NULL; 629 int isipv6; 630 #else 631 const void *ip6 = NULL; 632 #endif /* INET6 */ 633 struct tcpopt to; /* options in this segment */ 634 char *s = NULL; /* address and port logging */ 635 636 NET_EPOCH_ASSERT(); 637 638 #ifdef INET6 639 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 640 #endif 641 642 off0 = *offp; 643 m = *mp; 644 *mp = NULL; 645 to.to_flags = 0; 646 TCPSTAT_INC(tcps_rcvtotal); 647 648 #ifdef INET6 649 if (isipv6) { 650 ip6 = mtod(m, struct ip6_hdr *); 651 th = (struct tcphdr *)((caddr_t)ip6 + off0); 652 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 653 if (port) 654 goto skip6_csum; 655 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 656 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 657 th->th_sum = m->m_pkthdr.csum_data; 658 else 659 th->th_sum = in6_cksum_pseudo(ip6, tlen, 660 IPPROTO_TCP, m->m_pkthdr.csum_data); 661 th->th_sum ^= 0xffff; 662 } else 663 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 664 if (th->th_sum) { 665 TCPSTAT_INC(tcps_rcvbadsum); 666 goto drop; 667 } 668 skip6_csum: 669 /* 670 * Be proactive about unspecified IPv6 address in source. 671 * As we use all-zero to indicate unbounded/unconnected pcb, 672 * unspecified IPv6 address can be used to confuse us. 673 * 674 * Note that packets with unspecified IPv6 destination is 675 * already dropped in ip6_input. 676 */ 677 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 678 ("%s: unspecified destination v6 address", __func__)); 679 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 680 IP6STAT_INC(ip6s_badscope); /* XXX */ 681 goto drop; 682 } 683 iptos = IPV6_TRAFFIC_CLASS(ip6); 684 } 685 #endif 686 #if defined(INET) && defined(INET6) 687 else 688 #endif 689 #ifdef INET 690 { 691 /* 692 * Get IP and TCP header together in first mbuf. 693 * Note: IP leaves IP header in first mbuf. 694 */ 695 if (off0 > sizeof (struct ip)) { 696 ip_stripoptions(m); 697 off0 = sizeof(struct ip); 698 } 699 if (m->m_len < sizeof (struct tcpiphdr)) { 700 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 701 == NULL) { 702 TCPSTAT_INC(tcps_rcvshort); 703 return (IPPROTO_DONE); 704 } 705 } 706 ip = mtod(m, struct ip *); 707 th = (struct tcphdr *)((caddr_t)ip + off0); 708 tlen = ntohs(ip->ip_len) - off0; 709 710 iptos = ip->ip_tos; 711 if (port) 712 goto skip_csum; 713 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 714 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 715 th->th_sum = m->m_pkthdr.csum_data; 716 else 717 th->th_sum = in_pseudo(ip->ip_src.s_addr, 718 ip->ip_dst.s_addr, 719 htonl(m->m_pkthdr.csum_data + tlen + 720 IPPROTO_TCP)); 721 th->th_sum ^= 0xffff; 722 } else { 723 struct ipovly *ipov = (struct ipovly *)ip; 724 725 /* 726 * Checksum extended TCP header and data. 727 */ 728 len = off0 + tlen; 729 ipttl = ip->ip_ttl; 730 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 731 ipov->ih_len = htons(tlen); 732 th->th_sum = in_cksum(m, len); 733 /* Reset length for SDT probes. */ 734 ip->ip_len = htons(len); 735 /* Reset TOS bits */ 736 ip->ip_tos = iptos; 737 /* Re-initialization for later version check */ 738 ip->ip_ttl = ipttl; 739 ip->ip_v = IPVERSION; 740 ip->ip_hl = off0 >> 2; 741 } 742 skip_csum: 743 if (th->th_sum && (port == 0)) { 744 TCPSTAT_INC(tcps_rcvbadsum); 745 goto drop; 746 } 747 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 748 ("%s: unspecified destination v4 address", __func__)); 749 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 750 IPSTAT_INC(ips_badaddr); 751 goto drop; 752 } 753 } 754 #endif /* INET */ 755 756 /* 757 * Check that TCP offset makes sense, 758 * pull out TCP options and adjust length. XXX 759 */ 760 off = th->th_off << 2; 761 if (off < sizeof (struct tcphdr) || off > tlen) { 762 TCPSTAT_INC(tcps_rcvbadoff); 763 goto drop; 764 } 765 tlen -= off; /* tlen is used instead of ti->ti_len */ 766 if (off > sizeof (struct tcphdr)) { 767 #ifdef INET6 768 if (isipv6) { 769 if (m->m_len < off0 + off) { 770 m = m_pullup(m, off0 + off); 771 if (m == NULL) { 772 TCPSTAT_INC(tcps_rcvshort); 773 return (IPPROTO_DONE); 774 } 775 } 776 ip6 = mtod(m, struct ip6_hdr *); 777 th = (struct tcphdr *)((caddr_t)ip6 + off0); 778 } 779 #endif 780 #if defined(INET) && defined(INET6) 781 else 782 #endif 783 #ifdef INET 784 { 785 if (m->m_len < sizeof(struct ip) + off) { 786 if ((m = m_pullup(m, sizeof (struct ip) + off)) 787 == NULL) { 788 TCPSTAT_INC(tcps_rcvshort); 789 return (IPPROTO_DONE); 790 } 791 ip = mtod(m, struct ip *); 792 th = (struct tcphdr *)((caddr_t)ip + off0); 793 } 794 } 795 #endif 796 optlen = off - sizeof (struct tcphdr); 797 optp = (u_char *)(th + 1); 798 } 799 thflags = tcp_get_flags(th); 800 801 /* 802 * Convert TCP protocol specific fields to host format. 803 */ 804 tcp_fields_to_host(th); 805 806 /* 807 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 808 */ 809 drop_hdrlen = off0 + off; 810 811 /* 812 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 813 */ 814 if ( 815 #ifdef INET6 816 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 817 #ifdef INET 818 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 819 #endif 820 #endif 821 #if defined(INET) && !defined(INET6) 822 (m->m_flags & M_IP_NEXTHOP) 823 #endif 824 ) 825 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 826 827 /* 828 * For initial SYN packets we don't need write lock on matching 829 * PCB, be it a listening one or a synchronized one. The packet 830 * shall not modify its state. 831 */ 832 lookupflag = INPLOOKUP_WILDCARD | 833 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 834 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB); 835 findpcb: 836 #ifdef INET6 837 if (isipv6 && fwd_tag != NULL) { 838 struct sockaddr_in6 *next_hop6; 839 840 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 841 /* 842 * Transparently forwarded. Pretend to be the destination. 843 * Already got one like this? 844 */ 845 inp = in6_pcblookup_mbuf(&V_tcbinfo, 846 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 847 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 848 if (!inp) { 849 /* 850 * It's new. Try to find the ambushing socket. 851 * Because we've rewritten the destination address, 852 * any hardware-generated hash is ignored. 853 */ 854 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 855 th->th_sport, &next_hop6->sin6_addr, 856 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 857 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 858 } 859 } else if (isipv6) { 860 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 861 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 862 m->m_pkthdr.rcvif, m); 863 } 864 #endif /* INET6 */ 865 #if defined(INET6) && defined(INET) 866 else 867 #endif 868 #ifdef INET 869 if (fwd_tag != NULL) { 870 struct sockaddr_in *next_hop; 871 872 next_hop = (struct sockaddr_in *)(fwd_tag+1); 873 /* 874 * Transparently forwarded. Pretend to be the destination. 875 * already got one like this? 876 */ 877 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 878 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 879 m->m_pkthdr.rcvif, m); 880 if (!inp) { 881 /* 882 * It's new. Try to find the ambushing socket. 883 * Because we've rewritten the destination address, 884 * any hardware-generated hash is ignored. 885 */ 886 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 887 th->th_sport, next_hop->sin_addr, 888 next_hop->sin_port ? ntohs(next_hop->sin_port) : 889 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 890 } 891 } else 892 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 893 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 894 m->m_pkthdr.rcvif, m); 895 #endif /* INET */ 896 897 /* 898 * If the INPCB does not exist then all data in the incoming 899 * segment is discarded and an appropriate RST is sent back. 900 * XXX MRT Send RST using which routing table? 901 */ 902 if (inp == NULL) { 903 if (rstreason != 0) { 904 /* We came here after second (safety) lookup. */ 905 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 906 goto dropwithreset; 907 } 908 /* 909 * Log communication attempts to ports that are not 910 * in use. 911 */ 912 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 913 V_tcp_log_in_vain == 2) { 914 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 915 log(LOG_INFO, "%s; %s: Connection attempt " 916 "to closed port\n", s, __func__); 917 } 918 /* 919 * When blackholing do not respond with a RST but 920 * completely ignore the segment and drop it. 921 */ 922 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 923 V_blackhole == 2) && (V_blackhole_local || ( 924 #ifdef INET6 925 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 926 #endif 927 #ifdef INET 928 !in_localip(ip->ip_src) 929 #else 930 true 931 #endif 932 ))) 933 goto dropunlock; 934 935 rstreason = BANDLIM_RST_CLOSEDPORT; 936 goto dropwithreset; 937 } 938 INP_LOCK_ASSERT(inp); 939 940 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 941 !SOLISTENING(inp->inp_socket)) { 942 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 943 inp->inp_flowid = m->m_pkthdr.flowid; 944 inp->inp_flowtype = M_HASHTYPE_GET(m); 945 #ifdef RSS 946 } else { 947 /* assign flowid by software RSS hash */ 948 #ifdef INET6 949 if (isipv6) { 950 rss_proto_software_hash_v6(&inp->in6p_faddr, 951 &inp->in6p_laddr, 952 inp->inp_fport, 953 inp->inp_lport, 954 IPPROTO_TCP, 955 &inp->inp_flowid, 956 &inp->inp_flowtype); 957 } else 958 #endif /* INET6 */ 959 { 960 rss_proto_software_hash_v4(inp->inp_faddr, 961 inp->inp_laddr, 962 inp->inp_fport, 963 inp->inp_lport, 964 IPPROTO_TCP, 965 &inp->inp_flowid, 966 &inp->inp_flowtype); 967 } 968 #endif /* RSS */ 969 } 970 } 971 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 972 #ifdef INET6 973 if (isipv6 && IPSEC_ENABLED(ipv6) && 974 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 975 goto dropunlock; 976 } 977 #ifdef INET 978 else 979 #endif 980 #endif /* INET6 */ 981 #ifdef INET 982 if (IPSEC_ENABLED(ipv4) && 983 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 984 goto dropunlock; 985 } 986 #endif /* INET */ 987 #endif /* IPSEC */ 988 989 /* 990 * Check the minimum TTL for socket. 991 */ 992 if (inp->inp_ip_minttl != 0) { 993 #ifdef INET6 994 if (isipv6) { 995 if (inp->inp_ip_minttl > ip6->ip6_hlim) 996 goto dropunlock; 997 } else 998 #endif 999 if (inp->inp_ip_minttl > ip->ip_ttl) 1000 goto dropunlock; 1001 } 1002 1003 tp = intotcpcb(inp); 1004 switch (tp->t_state) { 1005 case TCPS_TIME_WAIT: 1006 /* 1007 * A previous connection in TIMEWAIT state is supposed to catch 1008 * stray or duplicate segments arriving late. If this segment 1009 * was a legitimate new connection attempt, the old INPCB gets 1010 * removed and we can try again to find a listening socket. 1011 */ 1012 tcp_dooptions(&to, optp, optlen, 1013 (thflags & TH_SYN) ? TO_SYN : 0); 1014 /* 1015 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1016 */ 1017 if (tcp_twcheck(inp, &to, th, m, tlen)) 1018 goto findpcb; 1019 return (IPPROTO_DONE); 1020 case TCPS_CLOSED: 1021 /* 1022 * The TCPCB may no longer exist if the connection is winding 1023 * down or it is in the CLOSED state. Either way we drop the 1024 * segment and send an appropriate response. 1025 */ 1026 rstreason = BANDLIM_RST_CLOSEDPORT; 1027 goto dropwithreset; 1028 } 1029 1030 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1031 rstreason = BANDLIM_RST_CLOSEDPORT; 1032 goto dropwithreset; 1033 } 1034 1035 #ifdef TCP_OFFLOAD 1036 if (tp->t_flags & TF_TOE) { 1037 tcp_offload_input(tp, m); 1038 m = NULL; /* consumed by the TOE driver */ 1039 goto dropunlock; 1040 } 1041 #endif 1042 1043 #ifdef MAC 1044 if (mac_inpcb_check_deliver(inp, m)) 1045 goto dropunlock; 1046 #endif 1047 so = inp->inp_socket; 1048 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1049 /* 1050 * When the socket is accepting connections (the INPCB is in LISTEN 1051 * state) we look into the SYN cache if this is a new connection 1052 * attempt or the completion of a previous one. 1053 */ 1054 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1055 ("%s: so accepting but tp %p not listening", __func__, tp)); 1056 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1057 struct in_conninfo inc; 1058 1059 bzero(&inc, sizeof(inc)); 1060 #ifdef INET6 1061 if (isipv6) { 1062 inc.inc_flags |= INC_ISIPV6; 1063 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1064 inc.inc_flags |= INC_IPV6MINMTU; 1065 inc.inc6_faddr = ip6->ip6_src; 1066 inc.inc6_laddr = ip6->ip6_dst; 1067 } else 1068 #endif 1069 { 1070 inc.inc_faddr = ip->ip_src; 1071 inc.inc_laddr = ip->ip_dst; 1072 } 1073 inc.inc_fport = th->th_sport; 1074 inc.inc_lport = th->th_dport; 1075 inc.inc_fibnum = so->so_fibnum; 1076 1077 /* 1078 * Check for an existing connection attempt in syncache if 1079 * the flag is only ACK. A successful lookup creates a new 1080 * socket appended to the listen queue in SYN_RECEIVED state. 1081 */ 1082 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1083 /* 1084 * Parse the TCP options here because 1085 * syncookies need access to the reflected 1086 * timestamp. 1087 */ 1088 tcp_dooptions(&to, optp, optlen, 0); 1089 /* 1090 * NB: syncache_expand() doesn't unlock inp. 1091 */ 1092 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1093 if (rstreason < 0) { 1094 /* 1095 * A failing TCP MD5 signature comparison 1096 * must result in the segment being dropped 1097 * and must not produce any response back 1098 * to the sender. 1099 */ 1100 goto dropunlock; 1101 } else if (rstreason == 0) { 1102 /* 1103 * No syncache entry, or ACK was not for our 1104 * SYN/ACK. Do our protection against double 1105 * ACK. If peer sent us 2 ACKs, then for the 1106 * first one syncache_expand() successfully 1107 * converted syncache entry into a socket, 1108 * while we were waiting on the inpcb lock. We 1109 * don't want to sent RST for the second ACK, 1110 * so we perform second lookup without wildcard 1111 * match, hoping to find the new socket. If 1112 * the ACK is stray indeed, rstreason would 1113 * hint the above code that the lookup was a 1114 * second attempt. 1115 * 1116 * NB: syncache did its own logging 1117 * of the failure cause. 1118 */ 1119 INP_WUNLOCK(inp); 1120 rstreason = BANDLIM_RST_OPENPORT; 1121 lookupflag &= ~INPLOOKUP_WILDCARD; 1122 goto findpcb; 1123 } 1124 tfo_socket_result: 1125 if (so == NULL) { 1126 /* 1127 * We completed the 3-way handshake 1128 * but could not allocate a socket 1129 * either due to memory shortage, 1130 * listen queue length limits or 1131 * global socket limits. Send RST 1132 * or wait and have the remote end 1133 * retransmit the ACK for another 1134 * try. 1135 */ 1136 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1137 log(LOG_DEBUG, "%s; %s: Listen socket: " 1138 "Socket allocation failed due to " 1139 "limits or memory shortage, %s\n", 1140 s, __func__, 1141 V_tcp_sc_rst_sock_fail ? 1142 "sending RST" : "try again"); 1143 if (V_tcp_sc_rst_sock_fail) { 1144 rstreason = BANDLIM_UNLIMITED; 1145 goto dropwithreset; 1146 } else 1147 goto dropunlock; 1148 } 1149 /* 1150 * Socket is created in state SYN_RECEIVED. 1151 * Unlock the listen socket, lock the newly 1152 * created socket and update the tp variable. 1153 * If we came here via jump to tfo_socket_result, 1154 * then listening socket is read-locked. 1155 */ 1156 INP_UNLOCK(inp); /* listen socket */ 1157 inp = sotoinpcb(so); 1158 /* 1159 * New connection inpcb is already locked by 1160 * syncache_expand(). 1161 */ 1162 INP_WLOCK_ASSERT(inp); 1163 tp = intotcpcb(inp); 1164 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1165 ("%s: ", __func__)); 1166 /* 1167 * Process the segment and the data it 1168 * contains. tcp_do_segment() consumes 1169 * the mbuf chain and unlocks the inpcb. 1170 */ 1171 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1172 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1173 tlen, iptos); 1174 return (IPPROTO_DONE); 1175 } 1176 /* 1177 * Segment flag validation for new connection attempts: 1178 * 1179 * Our (SYN|ACK) response was rejected. 1180 * Check with syncache and remove entry to prevent 1181 * retransmits. 1182 * 1183 * NB: syncache_chkrst does its own logging of failure 1184 * causes. 1185 */ 1186 if (thflags & TH_RST) { 1187 syncache_chkrst(&inc, th, m, port); 1188 goto dropunlock; 1189 } 1190 /* 1191 * We can't do anything without SYN. 1192 */ 1193 if ((thflags & TH_SYN) == 0) { 1194 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1195 log(LOG_DEBUG, "%s; %s: Listen socket: " 1196 "SYN is missing, segment ignored\n", 1197 s, __func__); 1198 TCPSTAT_INC(tcps_badsyn); 1199 goto dropunlock; 1200 } 1201 /* 1202 * (SYN|ACK) is bogus on a listen socket. 1203 */ 1204 if (thflags & TH_ACK) { 1205 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1206 log(LOG_DEBUG, "%s; %s: Listen socket: " 1207 "SYN|ACK invalid, segment rejected\n", 1208 s, __func__); 1209 syncache_badack(&inc, port); /* XXX: Not needed! */ 1210 TCPSTAT_INC(tcps_badsyn); 1211 rstreason = BANDLIM_RST_OPENPORT; 1212 goto dropwithreset; 1213 } 1214 /* 1215 * If the drop_synfin option is enabled, drop all 1216 * segments with both the SYN and FIN bits set. 1217 * This prevents e.g. nmap from identifying the 1218 * TCP/IP stack. 1219 * XXX: Poor reasoning. nmap has other methods 1220 * and is constantly refining its stack detection 1221 * strategies. 1222 * XXX: This is a violation of the TCP specification 1223 * and was used by RFC1644. 1224 */ 1225 if ((thflags & TH_FIN) && V_drop_synfin) { 1226 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1227 log(LOG_DEBUG, "%s; %s: Listen socket: " 1228 "SYN|FIN segment ignored (based on " 1229 "sysctl setting)\n", s, __func__); 1230 TCPSTAT_INC(tcps_badsyn); 1231 goto dropunlock; 1232 } 1233 /* 1234 * Segment's flags are (SYN) or (SYN|FIN). 1235 * 1236 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1237 * as they do not affect the state of the TCP FSM. 1238 * The data pointed to by TH_URG and th_urp is ignored. 1239 */ 1240 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1241 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1242 KASSERT(thflags & (TH_SYN), 1243 ("%s: Listen socket: TH_SYN not set", __func__)); 1244 INP_RLOCK_ASSERT(inp); 1245 #ifdef INET6 1246 /* 1247 * If deprecated address is forbidden, 1248 * we do not accept SYN to deprecated interface 1249 * address to prevent any new inbound connection from 1250 * getting established. 1251 * When we do not accept SYN, we send a TCP RST, 1252 * with deprecated source address (instead of dropping 1253 * it). We compromise it as it is much better for peer 1254 * to send a RST, and RST will be the final packet 1255 * for the exchange. 1256 * 1257 * If we do not forbid deprecated addresses, we accept 1258 * the SYN packet. RFC2462 does not suggest dropping 1259 * SYN in this case. 1260 * If we decipher RFC2462 5.5.4, it says like this: 1261 * 1. use of deprecated addr with existing 1262 * communication is okay - "SHOULD continue to be 1263 * used" 1264 * 2. use of it with new communication: 1265 * (2a) "SHOULD NOT be used if alternate address 1266 * with sufficient scope is available" 1267 * (2b) nothing mentioned otherwise. 1268 * Here we fall into (2b) case as we have no choice in 1269 * our source address selection - we must obey the peer. 1270 * 1271 * The wording in RFC2462 is confusing, and there are 1272 * multiple description text for deprecated address 1273 * handling - worse, they are not exactly the same. 1274 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1275 */ 1276 if (isipv6 && !V_ip6_use_deprecated) { 1277 struct in6_ifaddr *ia6; 1278 1279 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1280 if (ia6 != NULL && 1281 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1282 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1283 log(LOG_DEBUG, "%s; %s: Listen socket: " 1284 "Connection attempt to deprecated " 1285 "IPv6 address rejected\n", 1286 s, __func__); 1287 rstreason = BANDLIM_RST_OPENPORT; 1288 goto dropwithreset; 1289 } 1290 } 1291 #endif /* INET6 */ 1292 /* 1293 * Basic sanity checks on incoming SYN requests: 1294 * Don't respond if the destination is a link layer 1295 * broadcast according to RFC1122 4.2.3.10, p. 104. 1296 * If it is from this socket it must be forged. 1297 * Don't respond if the source or destination is a 1298 * global or subnet broad- or multicast address. 1299 * Note that it is quite possible to receive unicast 1300 * link-layer packets with a broadcast IP address. Use 1301 * in_broadcast() to find them. 1302 */ 1303 if (m->m_flags & (M_BCAST|M_MCAST)) { 1304 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1305 log(LOG_DEBUG, "%s; %s: Listen socket: " 1306 "Connection attempt from broad- or multicast " 1307 "link layer address ignored\n", s, __func__); 1308 goto dropunlock; 1309 } 1310 #ifdef INET6 1311 if (isipv6) { 1312 if (th->th_dport == th->th_sport && 1313 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1314 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1315 log(LOG_DEBUG, "%s; %s: Listen socket: " 1316 "Connection attempt to/from self " 1317 "ignored\n", s, __func__); 1318 goto dropunlock; 1319 } 1320 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1321 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1322 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1323 log(LOG_DEBUG, "%s; %s: Listen socket: " 1324 "Connection attempt from/to multicast " 1325 "address ignored\n", s, __func__); 1326 goto dropunlock; 1327 } 1328 } 1329 #endif 1330 #if defined(INET) && defined(INET6) 1331 else 1332 #endif 1333 #ifdef INET 1334 { 1335 if (th->th_dport == th->th_sport && 1336 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1337 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1338 log(LOG_DEBUG, "%s; %s: Listen socket: " 1339 "Connection attempt from/to self " 1340 "ignored\n", s, __func__); 1341 goto dropunlock; 1342 } 1343 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1344 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1345 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1346 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1347 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1348 log(LOG_DEBUG, "%s; %s: Listen socket: " 1349 "Connection attempt from/to broad- " 1350 "or multicast address ignored\n", 1351 s, __func__); 1352 goto dropunlock; 1353 } 1354 } 1355 #endif 1356 /* 1357 * SYN appears to be valid. Create compressed TCP state 1358 * for syncache. 1359 */ 1360 TCP_PROBE3(debug__input, tp, th, m); 1361 tcp_dooptions(&to, optp, optlen, TO_SYN); 1362 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1363 iptos, port)) != NULL) 1364 goto tfo_socket_result; 1365 1366 /* 1367 * Entry added to syncache and mbuf consumed. 1368 * Only the listen socket is unlocked by syncache_add(). 1369 */ 1370 return (IPPROTO_DONE); 1371 } else if (tp->t_state == TCPS_LISTEN) { 1372 /* 1373 * When a listen socket is torn down the SO_ACCEPTCONN 1374 * flag is removed first while connections are drained 1375 * from the accept queue in a unlock/lock cycle of the 1376 * ACCEPT_LOCK, opening a race condition allowing a SYN 1377 * attempt go through unhandled. 1378 */ 1379 goto dropunlock; 1380 } 1381 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1382 if (tp->t_flags & TF_SIGNATURE) { 1383 tcp_dooptions(&to, optp, optlen, thflags); 1384 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1385 TCPSTAT_INC(tcps_sig_err_nosigopt); 1386 goto dropunlock; 1387 } 1388 if (!TCPMD5_ENABLED() || 1389 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1390 goto dropunlock; 1391 } 1392 #endif 1393 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1394 1395 /* 1396 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1397 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1398 * the inpcb, and unlocks pcbinfo. 1399 * 1400 * XXXGL: in case of a pure SYN arriving on existing connection 1401 * TCP stacks won't need to modify the PCB, they would either drop 1402 * the segment silently, or send a challenge ACK. However, we try 1403 * to upgrade the lock, because calling convention for stacks is 1404 * write-lock on PCB. If upgrade fails, drop the SYN. 1405 */ 1406 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1407 goto dropunlock; 1408 1409 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1410 return (IPPROTO_DONE); 1411 1412 dropwithreset: 1413 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1414 1415 if (inp != NULL) { 1416 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1417 INP_UNLOCK(inp); 1418 } else 1419 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1420 m = NULL; /* mbuf chain got consumed. */ 1421 goto drop; 1422 1423 dropunlock: 1424 if (m != NULL) 1425 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1426 1427 if (inp != NULL) 1428 INP_UNLOCK(inp); 1429 1430 drop: 1431 if (s != NULL) 1432 free(s, M_TCPLOG); 1433 if (m != NULL) 1434 m_freem(m); 1435 return (IPPROTO_DONE); 1436 } 1437 1438 /* 1439 * Automatic sizing of receive socket buffer. Often the send 1440 * buffer size is not optimally adjusted to the actual network 1441 * conditions at hand (delay bandwidth product). Setting the 1442 * buffer size too small limits throughput on links with high 1443 * bandwidth and high delay (eg. trans-continental/oceanic links). 1444 * 1445 * On the receive side the socket buffer memory is only rarely 1446 * used to any significant extent. This allows us to be much 1447 * more aggressive in scaling the receive socket buffer. For 1448 * the case that the buffer space is actually used to a large 1449 * extent and we run out of kernel memory we can simply drop 1450 * the new segments; TCP on the sender will just retransmit it 1451 * later. Setting the buffer size too big may only consume too 1452 * much kernel memory if the application doesn't read() from 1453 * the socket or packet loss or reordering makes use of the 1454 * reassembly queue. 1455 * 1456 * The criteria to step up the receive buffer one notch are: 1457 * 1. Application has not set receive buffer size with 1458 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1459 * 2. the number of bytes received during 1/2 of an sRTT 1460 * is at least 3/8 of the current socket buffer size. 1461 * 3. receive buffer size has not hit maximal automatic size; 1462 * 1463 * If all of the criteria are met we increaset the socket buffer 1464 * by a 1/2 (bounded by the max). This allows us to keep ahead 1465 * of slow-start but also makes it so our peer never gets limited 1466 * by our rwnd which we then open up causing a burst. 1467 * 1468 * This algorithm does two steps per RTT at most and only if 1469 * we receive a bulk stream w/o packet losses or reorderings. 1470 * Shrinking the buffer during idle times is not necessary as 1471 * it doesn't consume any memory when idle. 1472 * 1473 * TODO: Only step up if the application is actually serving 1474 * the buffer to better manage the socket buffer resources. 1475 */ 1476 int 1477 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1478 struct tcpcb *tp, int tlen) 1479 { 1480 int newsize = 0; 1481 1482 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1483 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1484 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1485 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1486 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1487 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1488 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1489 } 1490 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1491 1492 /* Start over with next RTT. */ 1493 tp->rfbuf_ts = 0; 1494 tp->rfbuf_cnt = 0; 1495 } else { 1496 tp->rfbuf_cnt += tlen; /* add up */ 1497 } 1498 return (newsize); 1499 } 1500 1501 int 1502 tcp_input(struct mbuf **mp, int *offp, int proto) 1503 { 1504 return(tcp_input_with_port(mp, offp, proto, 0)); 1505 } 1506 1507 static void 1508 tcp_handle_wakeup(struct tcpcb *tp) 1509 { 1510 1511 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1512 1513 if (tp->t_flags & TF_WAKESOR) { 1514 struct socket *so = tptosocket(tp); 1515 1516 tp->t_flags &= ~TF_WAKESOR; 1517 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1518 sorwakeup_locked(so); 1519 } 1520 } 1521 1522 void 1523 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1524 int drop_hdrlen, int tlen, uint8_t iptos) 1525 { 1526 uint16_t thflags; 1527 int acked, ourfinisacked, needoutput = 0, sack_changed; 1528 int rstreason, todrop, win, incforsyn = 0; 1529 uint32_t tiwin; 1530 uint16_t nsegs; 1531 char *s; 1532 struct inpcb *inp = tptoinpcb(tp); 1533 struct socket *so = tptosocket(tp); 1534 struct in_conninfo *inc = &inp->inp_inc; 1535 struct mbuf *mfree; 1536 struct tcpopt to; 1537 int tfo_syn; 1538 u_int maxseg; 1539 1540 thflags = tcp_get_flags(th); 1541 tp->sackhint.last_sack_ack = 0; 1542 sack_changed = 0; 1543 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1544 1545 NET_EPOCH_ASSERT(); 1546 INP_WLOCK_ASSERT(inp); 1547 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1548 __func__)); 1549 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1550 __func__)); 1551 1552 #ifdef TCPPCAP 1553 /* Save segment, if requested. */ 1554 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1555 #endif 1556 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1557 tlen, NULL, true); 1558 1559 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1560 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1561 log(LOG_DEBUG, "%s; %s: " 1562 "SYN|FIN segment ignored (based on " 1563 "sysctl setting)\n", s, __func__); 1564 free(s, M_TCPLOG); 1565 } 1566 goto drop; 1567 } 1568 1569 /* 1570 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1571 * check SEQ.ACK first. 1572 */ 1573 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1574 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1575 rstreason = BANDLIM_UNLIMITED; 1576 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1577 goto dropwithreset; 1578 } 1579 1580 /* 1581 * Segment received on connection. 1582 * Reset idle time and keep-alive timer. 1583 * XXX: This should be done after segment 1584 * validation to ignore broken/spoofed segs. 1585 */ 1586 if (tp->t_idle_reduce && 1587 (tp->snd_max == tp->snd_una) && 1588 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1589 cc_after_idle(tp); 1590 tp->t_rcvtime = ticks; 1591 1592 if (thflags & TH_FIN) 1593 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1594 /* 1595 * Scale up the window into a 32-bit value. 1596 * For the SYN_SENT state the scale is zero. 1597 */ 1598 tiwin = th->th_win << tp->snd_scale; 1599 #ifdef STATS 1600 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1601 #endif 1602 1603 /* 1604 * TCP ECN processing. 1605 */ 1606 if (tcp_ecn_input_segment(tp, thflags, tlen, 1607 tcp_packets_this_ack(tp, th->th_ack), 1608 iptos)) 1609 cc_cong_signal(tp, th, CC_ECN); 1610 1611 /* 1612 * Parse options on any incoming segment. 1613 */ 1614 tcp_dooptions(&to, (u_char *)(th + 1), 1615 (th->th_off << 2) - sizeof(struct tcphdr), 1616 (thflags & TH_SYN) ? TO_SYN : 0); 1617 1618 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1619 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1620 (to.to_flags & TOF_SIGNATURE) == 0) { 1621 TCPSTAT_INC(tcps_sig_err_sigopt); 1622 /* XXX: should drop? */ 1623 } 1624 #endif 1625 /* 1626 * If echoed timestamp is later than the current time, 1627 * fall back to non RFC1323 RTT calculation. Normalize 1628 * timestamp if syncookies were used when this connection 1629 * was established. 1630 */ 1631 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1632 to.to_tsecr -= tp->ts_offset; 1633 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1634 to.to_tsecr = 0; 1635 else if (tp->t_rxtshift == 1 && 1636 tp->t_flags & TF_PREVVALID && 1637 tp->t_badrxtwin != 0 && 1638 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 1639 cc_cong_signal(tp, th, CC_RTO_ERR); 1640 } 1641 /* 1642 * Process options only when we get SYN/ACK back. The SYN case 1643 * for incoming connections is handled in tcp_syncache. 1644 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1645 * or <SYN,ACK>) segment itself is never scaled. 1646 * XXX this is traditional behavior, may need to be cleaned up. 1647 */ 1648 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1649 /* Handle parallel SYN for ECN */ 1650 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1651 if ((to.to_flags & TOF_SCALE) && 1652 (tp->t_flags & TF_REQ_SCALE) && 1653 !(tp->t_flags & TF_NOOPT)) { 1654 tp->t_flags |= TF_RCVD_SCALE; 1655 tp->snd_scale = to.to_wscale; 1656 } else 1657 tp->t_flags &= ~TF_REQ_SCALE; 1658 /* 1659 * Initial send window. It will be updated with 1660 * the next incoming segment to the scaled value. 1661 */ 1662 tp->snd_wnd = th->th_win; 1663 if ((to.to_flags & TOF_TS) && 1664 (tp->t_flags & TF_REQ_TSTMP) && 1665 !(tp->t_flags & TF_NOOPT)) { 1666 tp->t_flags |= TF_RCVD_TSTMP; 1667 tp->ts_recent = to.to_tsval; 1668 tp->ts_recent_age = tcp_ts_getticks(); 1669 } else 1670 tp->t_flags &= ~TF_REQ_TSTMP; 1671 if (to.to_flags & TOF_MSS) 1672 tcp_mss(tp, to.to_mss); 1673 if ((tp->t_flags & TF_SACK_PERMIT) && 1674 (!(to.to_flags & TOF_SACKPERM) || 1675 (tp->t_flags & TF_NOOPT))) 1676 tp->t_flags &= ~TF_SACK_PERMIT; 1677 if (IS_FASTOPEN(tp->t_flags)) { 1678 if ((to.to_flags & TOF_FASTOPEN) && 1679 !(tp->t_flags & TF_NOOPT)) { 1680 uint16_t mss; 1681 1682 if (to.to_flags & TOF_MSS) 1683 mss = to.to_mss; 1684 else 1685 if ((inp->inp_vflag & INP_IPV6) != 0) 1686 mss = TCP6_MSS; 1687 else 1688 mss = TCP_MSS; 1689 tcp_fastopen_update_cache(tp, mss, 1690 to.to_tfo_len, to.to_tfo_cookie); 1691 } else 1692 tcp_fastopen_disable_path(tp); 1693 } 1694 } 1695 1696 /* 1697 * If timestamps were negotiated during SYN/ACK and a 1698 * segment without a timestamp is received, silently drop 1699 * the segment, unless it is a RST segment or missing timestamps are 1700 * tolerated. 1701 * See section 3.2 of RFC 7323. 1702 */ 1703 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1704 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1705 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1706 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1707 "segment processed normally\n", 1708 s, __func__); 1709 free(s, M_TCPLOG); 1710 } 1711 } else { 1712 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1713 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1714 "segment silently dropped\n", s, __func__); 1715 free(s, M_TCPLOG); 1716 } 1717 goto drop; 1718 } 1719 } 1720 /* 1721 * If timestamps were not negotiated during SYN/ACK and a 1722 * segment with a timestamp is received, ignore the 1723 * timestamp and process the packet normally. 1724 * See section 3.2 of RFC 7323. 1725 */ 1726 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1727 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1728 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1729 "segment processed normally\n", s, __func__); 1730 free(s, M_TCPLOG); 1731 } 1732 } 1733 1734 /* 1735 * Header prediction: check for the two common cases 1736 * of a uni-directional data xfer. If the packet has 1737 * no control flags, is in-sequence, the window didn't 1738 * change and we're not retransmitting, it's a 1739 * candidate. If the length is zero and the ack moved 1740 * forward, we're the sender side of the xfer. Just 1741 * free the data acked & wake any higher level process 1742 * that was blocked waiting for space. If the length 1743 * is non-zero and the ack didn't move, we're the 1744 * receiver side. If we're getting packets in-order 1745 * (the reassembly queue is empty), add the data to 1746 * the socket buffer and note that we need a delayed ack. 1747 * Make sure that the hidden state-flags are also off. 1748 * Since we check for TCPS_ESTABLISHED first, it can only 1749 * be TH_NEEDSYN. 1750 */ 1751 if (tp->t_state == TCPS_ESTABLISHED && 1752 th->th_seq == tp->rcv_nxt && 1753 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1754 tp->snd_nxt == tp->snd_max && 1755 tiwin && tiwin == tp->snd_wnd && 1756 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1757 SEGQ_EMPTY(tp) && 1758 ((to.to_flags & TOF_TS) == 0 || 1759 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1760 /* 1761 * If last ACK falls within this segment's sequence numbers, 1762 * record the timestamp. 1763 * NOTE that the test is modified according to the latest 1764 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1765 */ 1766 if ((to.to_flags & TOF_TS) != 0 && 1767 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1768 tp->ts_recent_age = tcp_ts_getticks(); 1769 tp->ts_recent = to.to_tsval; 1770 } 1771 1772 if (tlen == 0) { 1773 if (SEQ_GT(th->th_ack, tp->snd_una) && 1774 SEQ_LEQ(th->th_ack, tp->snd_max) && 1775 !IN_RECOVERY(tp->t_flags) && 1776 (to.to_flags & TOF_SACK) == 0 && 1777 TAILQ_EMPTY(&tp->snd_holes)) { 1778 /* 1779 * This is a pure ack for outstanding data. 1780 */ 1781 TCPSTAT_INC(tcps_predack); 1782 1783 /* 1784 * "bad retransmit" recovery without timestamps. 1785 */ 1786 if ((to.to_flags & TOF_TS) == 0 && 1787 tp->t_rxtshift == 1 && 1788 tp->t_flags & TF_PREVVALID && 1789 tp->t_badrxtwin != 0 && 1790 TSTMP_LT(ticks, tp->t_badrxtwin)) { 1791 cc_cong_signal(tp, th, CC_RTO_ERR); 1792 } 1793 1794 /* 1795 * Recalculate the transmit timer / rtt. 1796 * 1797 * Some boxes send broken timestamp replies 1798 * during the SYN+ACK phase, ignore 1799 * timestamps of 0 or we could calculate a 1800 * huge RTT and blow up the retransmit timer. 1801 */ 1802 if ((to.to_flags & TOF_TS) != 0 && 1803 to.to_tsecr) { 1804 uint32_t t; 1805 1806 t = tcp_ts_getticks() - to.to_tsecr; 1807 if (!tp->t_rttlow || tp->t_rttlow > t) 1808 tp->t_rttlow = t; 1809 tcp_xmit_timer(tp, 1810 TCP_TS_TO_TICKS(t) + 1); 1811 } else if (tp->t_rtttime && 1812 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1813 if (!tp->t_rttlow || 1814 tp->t_rttlow > ticks - tp->t_rtttime) 1815 tp->t_rttlow = ticks - tp->t_rtttime; 1816 tcp_xmit_timer(tp, 1817 ticks - tp->t_rtttime); 1818 } 1819 acked = BYTES_THIS_ACK(tp, th); 1820 1821 #ifdef TCP_HHOOK 1822 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1823 hhook_run_tcp_est_in(tp, th, &to); 1824 #endif 1825 1826 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1827 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1828 sbdrop(&so->so_snd, acked); 1829 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1830 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1831 tp->snd_recover = th->th_ack - 1; 1832 1833 /* 1834 * Let the congestion control algorithm update 1835 * congestion control related information. This 1836 * typically means increasing the congestion 1837 * window. 1838 */ 1839 cc_ack_received(tp, th, nsegs, CC_ACK); 1840 1841 tp->snd_una = th->th_ack; 1842 /* 1843 * Pull snd_wl2 up to prevent seq wrap relative 1844 * to th_ack. 1845 */ 1846 tp->snd_wl2 = th->th_ack; 1847 tp->t_dupacks = 0; 1848 m_freem(m); 1849 1850 /* 1851 * If all outstanding data are acked, stop 1852 * retransmit timer, otherwise restart timer 1853 * using current (possibly backed-off) value. 1854 * If process is waiting for space, 1855 * wakeup/selwakeup/signal. If data 1856 * are ready to send, let tcp_output 1857 * decide between more output or persist. 1858 */ 1859 TCP_PROBE3(debug__input, tp, th, m); 1860 /* 1861 * Clear t_acktime if remote side has ACKd 1862 * all data in the socket buffer. 1863 * Otherwise, update t_acktime if we received 1864 * a sufficiently large ACK. 1865 */ 1866 if (sbavail(&so->so_snd) == 0) 1867 tp->t_acktime = 0; 1868 else if (acked > 1) 1869 tp->t_acktime = ticks; 1870 if (tp->snd_una == tp->snd_max) 1871 tcp_timer_activate(tp, TT_REXMT, 0); 1872 else if (!tcp_timer_active(tp, TT_PERSIST)) 1873 tcp_timer_activate(tp, TT_REXMT, 1874 TP_RXTCUR(tp)); 1875 sowwakeup(so); 1876 if (sbavail(&so->so_snd)) 1877 (void) tcp_output(tp); 1878 goto check_delack; 1879 } 1880 } else if (th->th_ack == tp->snd_una && 1881 tlen <= sbspace(&so->so_rcv)) { 1882 int newsize = 0; /* automatic sockbuf scaling */ 1883 1884 /* 1885 * This is a pure, in-sequence data packet with 1886 * nothing on the reassembly queue and we have enough 1887 * buffer space to take it. 1888 */ 1889 /* Clean receiver SACK report if present */ 1890 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1891 tcp_clean_sackreport(tp); 1892 TCPSTAT_INC(tcps_preddat); 1893 tp->rcv_nxt += tlen; 1894 if (tlen && 1895 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1896 (tp->t_fbyte_in == 0)) { 1897 tp->t_fbyte_in = ticks; 1898 if (tp->t_fbyte_in == 0) 1899 tp->t_fbyte_in = 1; 1900 if (tp->t_fbyte_out && tp->t_fbyte_in) 1901 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1902 } 1903 /* 1904 * Pull snd_wl1 up to prevent seq wrap relative to 1905 * th_seq. 1906 */ 1907 tp->snd_wl1 = th->th_seq; 1908 /* 1909 * Pull rcv_up up to prevent seq wrap relative to 1910 * rcv_nxt. 1911 */ 1912 tp->rcv_up = tp->rcv_nxt; 1913 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1914 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1915 TCP_PROBE3(debug__input, tp, th, m); 1916 1917 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1918 1919 /* Add data to socket buffer. */ 1920 SOCKBUF_LOCK(&so->so_rcv); 1921 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1922 m_freem(m); 1923 } else { 1924 /* 1925 * Set new socket buffer size. 1926 * Give up when limit is reached. 1927 */ 1928 if (newsize) 1929 if (!sbreserve_locked(so, SO_RCV, 1930 newsize, NULL)) 1931 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1932 m_adj(m, drop_hdrlen); /* delayed header drop */ 1933 sbappendstream_locked(&so->so_rcv, m, 0); 1934 } 1935 /* NB: sorwakeup_locked() does an implicit unlock. */ 1936 sorwakeup_locked(so); 1937 if (DELAY_ACK(tp, tlen)) { 1938 tp->t_flags |= TF_DELACK; 1939 } else { 1940 tp->t_flags |= TF_ACKNOW; 1941 tcp_output(tp); 1942 } 1943 goto check_delack; 1944 } 1945 } 1946 1947 /* 1948 * Calculate amount of space in receive window, 1949 * and then do TCP input processing. 1950 * Receive window is amount of space in rcv queue, 1951 * but not less than advertised window. 1952 */ 1953 win = sbspace(&so->so_rcv); 1954 if (win < 0) 1955 win = 0; 1956 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1957 1958 switch (tp->t_state) { 1959 /* 1960 * If the state is SYN_RECEIVED: 1961 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1962 */ 1963 case TCPS_SYN_RECEIVED: 1964 if (thflags & TH_RST) { 1965 /* Handle RST segments later. */ 1966 break; 1967 } 1968 if ((thflags & TH_ACK) && 1969 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1970 SEQ_GT(th->th_ack, tp->snd_max))) { 1971 rstreason = BANDLIM_RST_OPENPORT; 1972 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1973 goto dropwithreset; 1974 } 1975 if (IS_FASTOPEN(tp->t_flags)) { 1976 /* 1977 * When a TFO connection is in SYN_RECEIVED, the 1978 * only valid packets are the initial SYN, a 1979 * retransmit/copy of the initial SYN (possibly with 1980 * a subset of the original data), a valid ACK, a 1981 * FIN, or a RST. 1982 */ 1983 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1984 rstreason = BANDLIM_RST_OPENPORT; 1985 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1986 goto dropwithreset; 1987 } else if (thflags & TH_SYN) { 1988 /* non-initial SYN is ignored */ 1989 if ((tcp_timer_active(tp, TT_DELACK) || 1990 tcp_timer_active(tp, TT_REXMT))) 1991 goto drop; 1992 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1993 goto drop; 1994 } 1995 } 1996 break; 1997 1998 /* 1999 * If the state is SYN_SENT: 2000 * if seg contains a RST with valid ACK (SEQ.ACK has already 2001 * been verified), then drop the connection. 2002 * if seg contains a RST without an ACK, drop the seg. 2003 * if seg does not contain SYN, then drop the seg. 2004 * Otherwise this is an acceptable SYN segment 2005 * initialize tp->rcv_nxt and tp->irs 2006 * if seg contains ack then advance tp->snd_una 2007 * if seg contains an ECE and ECN support is enabled, the stream 2008 * is ECN capable. 2009 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2010 * arrange for segment to be acked (eventually) 2011 * continue processing rest of data/controls, beginning with URG 2012 */ 2013 case TCPS_SYN_SENT: 2014 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2015 TCP_PROBE5(connect__refused, NULL, tp, 2016 m, tp, th); 2017 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2018 tp = tcp_drop(tp, ECONNREFUSED); 2019 } 2020 if (thflags & TH_RST) 2021 goto drop; 2022 if (!(thflags & TH_SYN)) 2023 goto drop; 2024 2025 tp->irs = th->th_seq; 2026 tcp_rcvseqinit(tp); 2027 if (thflags & TH_ACK) { 2028 int tfo_partial_ack = 0; 2029 2030 TCPSTAT_INC(tcps_connects); 2031 soisconnected(so); 2032 #ifdef MAC 2033 mac_socketpeer_set_from_mbuf(m, so); 2034 #endif 2035 /* Do window scaling on this connection? */ 2036 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2037 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2038 tp->rcv_scale = tp->request_r_scale; 2039 } 2040 tp->rcv_adv += min(tp->rcv_wnd, 2041 TCP_MAXWIN << tp->rcv_scale); 2042 tp->snd_una++; /* SYN is acked */ 2043 /* 2044 * If not all the data that was sent in the TFO SYN 2045 * has been acked, resend the remainder right away. 2046 */ 2047 if (IS_FASTOPEN(tp->t_flags) && 2048 (tp->snd_una != tp->snd_max)) { 2049 tp->snd_nxt = th->th_ack; 2050 tfo_partial_ack = 1; 2051 } 2052 /* 2053 * If there's data, delay ACK; if there's also a FIN 2054 * ACKNOW will be turned on later. 2055 */ 2056 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2057 tcp_timer_activate(tp, TT_DELACK, 2058 tcp_delacktime); 2059 else 2060 tp->t_flags |= TF_ACKNOW; 2061 2062 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2063 2064 /* 2065 * Received <SYN,ACK> in SYN_SENT[*] state. 2066 * Transitions: 2067 * SYN_SENT --> ESTABLISHED 2068 * SYN_SENT* --> FIN_WAIT_1 2069 */ 2070 tp->t_starttime = ticks; 2071 if (tp->t_flags & TF_NEEDFIN) { 2072 tp->t_acktime = ticks; 2073 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2074 tp->t_flags &= ~TF_NEEDFIN; 2075 thflags &= ~TH_SYN; 2076 } else { 2077 tcp_state_change(tp, TCPS_ESTABLISHED); 2078 TCP_PROBE5(connect__established, NULL, tp, 2079 m, tp, th); 2080 cc_conn_init(tp); 2081 tcp_timer_activate(tp, TT_KEEP, 2082 TP_KEEPIDLE(tp)); 2083 } 2084 } else { 2085 /* 2086 * Received initial SYN in SYN-SENT[*] state => 2087 * simultaneous open. 2088 * If it succeeds, connection is * half-synchronized. 2089 * Otherwise, do 3-way handshake: 2090 * SYN-SENT -> SYN-RECEIVED 2091 * SYN-SENT* -> SYN-RECEIVED* 2092 */ 2093 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2094 tcp_timer_activate(tp, TT_REXMT, 0); 2095 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2096 } 2097 2098 /* 2099 * Advance th->th_seq to correspond to first data byte. 2100 * If data, trim to stay within window, 2101 * dropping FIN if necessary. 2102 */ 2103 th->th_seq++; 2104 if (tlen > tp->rcv_wnd) { 2105 todrop = tlen - tp->rcv_wnd; 2106 m_adj(m, -todrop); 2107 tlen = tp->rcv_wnd; 2108 thflags &= ~TH_FIN; 2109 TCPSTAT_INC(tcps_rcvpackafterwin); 2110 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2111 } 2112 tp->snd_wl1 = th->th_seq - 1; 2113 tp->rcv_up = th->th_seq; 2114 /* 2115 * Client side of transaction: already sent SYN and data. 2116 * If the remote host used T/TCP to validate the SYN, 2117 * our data will be ACK'd; if so, enter normal data segment 2118 * processing in the middle of step 5, ack processing. 2119 * Otherwise, goto step 6. 2120 */ 2121 if (thflags & TH_ACK) 2122 goto process_ACK; 2123 2124 goto step6; 2125 } 2126 2127 /* 2128 * States other than LISTEN or SYN_SENT. 2129 * First check the RST flag and sequence number since reset segments 2130 * are exempt from the timestamp and connection count tests. This 2131 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2132 * below which allowed reset segments in half the sequence space 2133 * to fall though and be processed (which gives forged reset 2134 * segments with a random sequence number a 50 percent chance of 2135 * killing a connection). 2136 * Then check timestamp, if present. 2137 * Then check the connection count, if present. 2138 * Then check that at least some bytes of segment are within 2139 * receive window. If segment begins before rcv_nxt, 2140 * drop leading data (and SYN); if nothing left, just ack. 2141 */ 2142 if (thflags & TH_RST) { 2143 /* 2144 * RFC5961 Section 3.2 2145 * 2146 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2147 * - If RST is in window, we send challenge ACK. 2148 * 2149 * Note: to take into account delayed ACKs, we should 2150 * test against last_ack_sent instead of rcv_nxt. 2151 * Note 2: we handle special case of closed window, not 2152 * covered by the RFC. 2153 */ 2154 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2155 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2156 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2157 KASSERT(tp->t_state != TCPS_SYN_SENT, 2158 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2159 __func__, th, tp)); 2160 2161 if (V_tcp_insecure_rst || 2162 tp->last_ack_sent == th->th_seq) { 2163 TCPSTAT_INC(tcps_drops); 2164 /* Drop the connection. */ 2165 switch (tp->t_state) { 2166 case TCPS_SYN_RECEIVED: 2167 so->so_error = ECONNREFUSED; 2168 goto close; 2169 case TCPS_ESTABLISHED: 2170 case TCPS_FIN_WAIT_1: 2171 case TCPS_FIN_WAIT_2: 2172 case TCPS_CLOSE_WAIT: 2173 case TCPS_CLOSING: 2174 case TCPS_LAST_ACK: 2175 so->so_error = ECONNRESET; 2176 close: 2177 /* FALLTHROUGH */ 2178 default: 2179 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2180 tp = tcp_close(tp); 2181 } 2182 } else { 2183 TCPSTAT_INC(tcps_badrst); 2184 /* Send challenge ACK. */ 2185 tcp_respond(tp, mtod(m, void *), th, m, 2186 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2187 tp->last_ack_sent = tp->rcv_nxt; 2188 m = NULL; 2189 } 2190 } 2191 goto drop; 2192 } 2193 2194 /* 2195 * RFC5961 Section 4.2 2196 * Send challenge ACK for any SYN in synchronized state. 2197 */ 2198 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2199 tp->t_state != TCPS_SYN_RECEIVED) { 2200 TCPSTAT_INC(tcps_badsyn); 2201 if (V_tcp_insecure_syn && 2202 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2203 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2204 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2205 tp = tcp_drop(tp, ECONNRESET); 2206 rstreason = BANDLIM_UNLIMITED; 2207 } else { 2208 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2209 /* Send challenge ACK. */ 2210 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2211 tp->snd_nxt, TH_ACK); 2212 tp->last_ack_sent = tp->rcv_nxt; 2213 m = NULL; 2214 } 2215 goto drop; 2216 } 2217 2218 /* 2219 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2220 * and it's less than ts_recent, drop it. 2221 */ 2222 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2223 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2224 /* Check to see if ts_recent is over 24 days old. */ 2225 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2226 /* 2227 * Invalidate ts_recent. If this segment updates 2228 * ts_recent, the age will be reset later and ts_recent 2229 * will get a valid value. If it does not, setting 2230 * ts_recent to zero will at least satisfy the 2231 * requirement that zero be placed in the timestamp 2232 * echo reply when ts_recent isn't valid. The 2233 * age isn't reset until we get a valid ts_recent 2234 * because we don't want out-of-order segments to be 2235 * dropped when ts_recent is old. 2236 */ 2237 tp->ts_recent = 0; 2238 } else { 2239 TCPSTAT_INC(tcps_rcvduppack); 2240 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2241 TCPSTAT_INC(tcps_pawsdrop); 2242 if (tlen) 2243 goto dropafterack; 2244 goto drop; 2245 } 2246 } 2247 2248 /* 2249 * In the SYN-RECEIVED state, validate that the packet belongs to 2250 * this connection before trimming the data to fit the receive 2251 * window. Check the sequence number versus IRS since we know 2252 * the sequence numbers haven't wrapped. This is a partial fix 2253 * for the "LAND" DoS attack. 2254 */ 2255 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2256 rstreason = BANDLIM_RST_OPENPORT; 2257 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2258 goto dropwithreset; 2259 } 2260 2261 todrop = tp->rcv_nxt - th->th_seq; 2262 if (todrop > 0) { 2263 if (thflags & TH_SYN) { 2264 thflags &= ~TH_SYN; 2265 th->th_seq++; 2266 if (th->th_urp > 1) 2267 th->th_urp--; 2268 else 2269 thflags &= ~TH_URG; 2270 todrop--; 2271 } 2272 /* 2273 * Following if statement from Stevens, vol. 2, p. 960. 2274 */ 2275 if (todrop > tlen 2276 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2277 /* 2278 * Any valid FIN must be to the left of the window. 2279 * At this point the FIN must be a duplicate or out 2280 * of sequence; drop it. 2281 */ 2282 thflags &= ~TH_FIN; 2283 2284 /* 2285 * Send an ACK to resynchronize and drop any data. 2286 * But keep on processing for RST or ACK. 2287 */ 2288 tp->t_flags |= TF_ACKNOW; 2289 todrop = tlen; 2290 TCPSTAT_INC(tcps_rcvduppack); 2291 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2292 } else { 2293 TCPSTAT_INC(tcps_rcvpartduppack); 2294 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2295 } 2296 /* 2297 * DSACK - add SACK block for dropped range 2298 */ 2299 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2300 tcp_update_sack_list(tp, th->th_seq, 2301 th->th_seq + todrop); 2302 /* 2303 * ACK now, as the next in-sequence segment 2304 * will clear the DSACK block again 2305 */ 2306 tp->t_flags |= TF_ACKNOW; 2307 } 2308 drop_hdrlen += todrop; /* drop from the top afterwards */ 2309 th->th_seq += todrop; 2310 tlen -= todrop; 2311 if (th->th_urp > todrop) 2312 th->th_urp -= todrop; 2313 else { 2314 thflags &= ~TH_URG; 2315 th->th_urp = 0; 2316 } 2317 } 2318 2319 /* 2320 * If new data are received on a connection after the 2321 * user processes are gone, then RST the other end. 2322 */ 2323 if ((tp->t_flags & TF_CLOSED) && tlen) { 2324 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2325 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2326 "after socket was closed, " 2327 "sending RST and removing tcpcb\n", 2328 s, __func__, tcpstates[tp->t_state], tlen); 2329 free(s, M_TCPLOG); 2330 } 2331 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2332 /* tcp_close will kill the inp pre-log the Reset */ 2333 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2334 tp = tcp_close(tp); 2335 TCPSTAT_INC(tcps_rcvafterclose); 2336 rstreason = BANDLIM_UNLIMITED; 2337 goto dropwithreset; 2338 } 2339 2340 /* 2341 * If segment ends after window, drop trailing data 2342 * (and PUSH and FIN); if nothing left, just ACK. 2343 */ 2344 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2345 if (todrop > 0) { 2346 TCPSTAT_INC(tcps_rcvpackafterwin); 2347 if (todrop >= tlen) { 2348 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2349 /* 2350 * If window is closed can only take segments at 2351 * window edge, and have to drop data and PUSH from 2352 * incoming segments. Continue processing, but 2353 * remember to ack. Otherwise, drop segment 2354 * and ack. 2355 */ 2356 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2357 tp->t_flags |= TF_ACKNOW; 2358 TCPSTAT_INC(tcps_rcvwinprobe); 2359 } else 2360 goto dropafterack; 2361 } else 2362 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2363 m_adj(m, -todrop); 2364 tlen -= todrop; 2365 thflags &= ~(TH_PUSH|TH_FIN); 2366 } 2367 2368 /* 2369 * If last ACK falls within this segment's sequence numbers, 2370 * record its timestamp. 2371 * NOTE: 2372 * 1) That the test incorporates suggestions from the latest 2373 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2374 * 2) That updating only on newer timestamps interferes with 2375 * our earlier PAWS tests, so this check should be solely 2376 * predicated on the sequence space of this segment. 2377 * 3) That we modify the segment boundary check to be 2378 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2379 * instead of RFC1323's 2380 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2381 * This modified check allows us to overcome RFC1323's 2382 * limitations as described in Stevens TCP/IP Illustrated 2383 * Vol. 2 p.869. In such cases, we can still calculate the 2384 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2385 */ 2386 if ((to.to_flags & TOF_TS) != 0 && 2387 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2388 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2389 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2390 tp->ts_recent_age = tcp_ts_getticks(); 2391 tp->ts_recent = to.to_tsval; 2392 } 2393 2394 /* 2395 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2396 * flag is on (half-synchronized state), then queue data for 2397 * later processing; else drop segment and return. 2398 */ 2399 if ((thflags & TH_ACK) == 0) { 2400 if (tp->t_state == TCPS_SYN_RECEIVED || 2401 (tp->t_flags & TF_NEEDSYN)) { 2402 if (tp->t_state == TCPS_SYN_RECEIVED && 2403 IS_FASTOPEN(tp->t_flags)) { 2404 tp->snd_wnd = tiwin; 2405 cc_conn_init(tp); 2406 } 2407 goto step6; 2408 } else if (tp->t_flags & TF_ACKNOW) 2409 goto dropafterack; 2410 else 2411 goto drop; 2412 } 2413 2414 /* 2415 * Ack processing. 2416 */ 2417 switch (tp->t_state) { 2418 /* 2419 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2420 * ESTABLISHED state and continue processing. 2421 * The ACK was checked above. 2422 */ 2423 case TCPS_SYN_RECEIVED: 2424 2425 TCPSTAT_INC(tcps_connects); 2426 if (tp->t_flags & TF_SONOTCONN) { 2427 /* 2428 * Usually SYN_RECEIVED had been created from a LISTEN, 2429 * and solisten_enqueue() has already marked the socket 2430 * layer as connected. If it didn't, which can happen 2431 * only with an accept_filter(9), then the tp is marked 2432 * with TF_SONOTCONN. The other reason for this mark 2433 * to be set is a simultaneous open, a SYN_RECEIVED 2434 * that had been created from SYN_SENT. 2435 */ 2436 tp->t_flags &= ~TF_SONOTCONN; 2437 soisconnected(so); 2438 } 2439 /* Do window scaling? */ 2440 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2441 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2442 tp->rcv_scale = tp->request_r_scale; 2443 } 2444 tp->snd_wnd = tiwin; 2445 /* 2446 * Make transitions: 2447 * SYN-RECEIVED -> ESTABLISHED 2448 * SYN-RECEIVED* -> FIN-WAIT-1 2449 */ 2450 tp->t_starttime = ticks; 2451 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2452 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2453 tp->t_tfo_pending = NULL; 2454 } 2455 if (tp->t_flags & TF_NEEDFIN) { 2456 tp->t_acktime = ticks; 2457 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2458 tp->t_flags &= ~TF_NEEDFIN; 2459 } else { 2460 tcp_state_change(tp, TCPS_ESTABLISHED); 2461 TCP_PROBE5(accept__established, NULL, tp, 2462 m, tp, th); 2463 /* 2464 * TFO connections call cc_conn_init() during SYN 2465 * processing. Calling it again here for such 2466 * connections is not harmless as it would undo the 2467 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2468 * is retransmitted. 2469 */ 2470 if (!IS_FASTOPEN(tp->t_flags)) 2471 cc_conn_init(tp); 2472 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2473 } 2474 /* 2475 * Account for the ACK of our SYN prior to 2476 * regular ACK processing below, except for 2477 * simultaneous SYN, which is handled later. 2478 */ 2479 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2480 incforsyn = 1; 2481 /* 2482 * If segment contains data or ACK, will call tcp_reass() 2483 * later; if not, do so now to pass queued data to user. 2484 */ 2485 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2486 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2487 (struct mbuf *)0); 2488 tcp_handle_wakeup(tp); 2489 } 2490 tp->snd_wl1 = th->th_seq - 1; 2491 /* FALLTHROUGH */ 2492 2493 /* 2494 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2495 * ACKs. If the ack is in the range 2496 * tp->snd_una < th->th_ack <= tp->snd_max 2497 * then advance tp->snd_una to th->th_ack and drop 2498 * data from the retransmission queue. If this ACK reflects 2499 * more up to date window information we update our window information. 2500 */ 2501 case TCPS_ESTABLISHED: 2502 case TCPS_FIN_WAIT_1: 2503 case TCPS_FIN_WAIT_2: 2504 case TCPS_CLOSE_WAIT: 2505 case TCPS_CLOSING: 2506 case TCPS_LAST_ACK: 2507 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2508 TCPSTAT_INC(tcps_rcvacktoomuch); 2509 goto dropafterack; 2510 } 2511 if (tcp_is_sack_recovery(tp, &to)) { 2512 if (((sack_changed = tcp_sack_doack(tp, &to, th->th_ack)) != 0) && 2513 (tp->t_flags & TF_LRD)) { 2514 tcp_sack_lost_retransmission(tp, th); 2515 } 2516 } else 2517 /* 2518 * Reset the value so that previous (valid) value 2519 * from the last ack with SACK doesn't get used. 2520 */ 2521 tp->sackhint.sacked_bytes = 0; 2522 2523 #ifdef TCP_HHOOK 2524 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2525 hhook_run_tcp_est_in(tp, th, &to); 2526 #endif 2527 2528 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2529 maxseg = tcp_maxseg(tp); 2530 if (tlen == 0 && 2531 (tiwin == tp->snd_wnd || 2532 (tp->t_flags & TF_SACK_PERMIT))) { 2533 /* 2534 * If this is the first time we've seen a 2535 * FIN from the remote, this is not a 2536 * duplicate and it needs to be processed 2537 * normally. This happens during a 2538 * simultaneous close. 2539 */ 2540 if ((thflags & TH_FIN) && 2541 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2542 tp->t_dupacks = 0; 2543 break; 2544 } 2545 TCPSTAT_INC(tcps_rcvdupack); 2546 /* 2547 * If we have outstanding data (other than 2548 * a window probe), this is a completely 2549 * duplicate ack (ie, window info didn't 2550 * change and FIN isn't set), 2551 * the ack is the biggest we've 2552 * seen and we've seen exactly our rexmt 2553 * threshold of them, assume a packet 2554 * has been dropped and retransmit it. 2555 * Kludge snd_nxt & the congestion 2556 * window so we send only this one 2557 * packet. 2558 * 2559 * We know we're losing at the current 2560 * window size so do congestion avoidance 2561 * (set ssthresh to half the current window 2562 * and pull our congestion window back to 2563 * the new ssthresh). 2564 * 2565 * Dup acks mean that packets have left the 2566 * network (they're now cached at the receiver) 2567 * so bump cwnd by the amount in the receiver 2568 * to keep a constant cwnd packets in the 2569 * network. 2570 * 2571 * When using TCP ECN, notify the peer that 2572 * we reduced the cwnd. 2573 */ 2574 /* 2575 * Following 2 kinds of acks should not affect 2576 * dupack counting: 2577 * 1) Old acks 2578 * 2) Acks with SACK but without any new SACK 2579 * information in them. These could result from 2580 * any anomaly in the network like a switch 2581 * duplicating packets or a possible DoS attack. 2582 */ 2583 if (th->th_ack != tp->snd_una || 2584 (tcp_is_sack_recovery(tp, &to) && 2585 !sack_changed)) 2586 break; 2587 else if (!tcp_timer_active(tp, TT_REXMT)) 2588 tp->t_dupacks = 0; 2589 else if (++tp->t_dupacks > tcprexmtthresh || 2590 IN_FASTRECOVERY(tp->t_flags)) { 2591 cc_ack_received(tp, th, nsegs, 2592 CC_DUPACK); 2593 if (V_tcp_do_prr && 2594 IN_FASTRECOVERY(tp->t_flags)) { 2595 tcp_do_prr_ack(tp, th, &to); 2596 } else if (tcp_is_sack_recovery(tp, &to) && 2597 IN_FASTRECOVERY(tp->t_flags)) { 2598 int awnd; 2599 2600 /* 2601 * Compute the amount of data in flight first. 2602 * We can inject new data into the pipe iff 2603 * we have less than 1/2 the original window's 2604 * worth of data in flight. 2605 */ 2606 if (V_tcp_do_newsack) 2607 awnd = tcp_compute_pipe(tp); 2608 else 2609 awnd = (tp->snd_nxt - tp->snd_fack) + 2610 tp->sackhint.sack_bytes_rexmit; 2611 2612 if (awnd < tp->snd_ssthresh) { 2613 tp->snd_cwnd += maxseg; 2614 if (tp->snd_cwnd > tp->snd_ssthresh) 2615 tp->snd_cwnd = tp->snd_ssthresh; 2616 } 2617 } else 2618 tp->snd_cwnd += maxseg; 2619 (void) tcp_output(tp); 2620 goto drop; 2621 } else if (tp->t_dupacks == tcprexmtthresh || 2622 (tp->t_flags & TF_SACK_PERMIT && 2623 V_tcp_do_newsack && 2624 tp->sackhint.sacked_bytes > 2625 (tcprexmtthresh - 1) * maxseg)) { 2626 enter_recovery: 2627 /* 2628 * Above is the RFC6675 trigger condition of 2629 * more than (dupthresh-1)*maxseg sacked data. 2630 * If the count of holes in the 2631 * scoreboard is >= dupthresh, we could 2632 * also enter loss recovery, but don't 2633 * have that value readily available. 2634 */ 2635 tp->t_dupacks = tcprexmtthresh; 2636 tcp_seq onxt = tp->snd_nxt; 2637 2638 /* 2639 * If we're doing sack, or prr, check 2640 * to see if we're already in sack 2641 * recovery. If we're not doing sack, 2642 * check to see if we're in newreno 2643 * recovery. 2644 */ 2645 if (V_tcp_do_prr || 2646 (tp->t_flags & TF_SACK_PERMIT)) { 2647 if (IN_FASTRECOVERY(tp->t_flags)) { 2648 tp->t_dupacks = 0; 2649 break; 2650 } 2651 } else { 2652 if (SEQ_LEQ(th->th_ack, 2653 tp->snd_recover)) { 2654 tp->t_dupacks = 0; 2655 break; 2656 } 2657 } 2658 /* Congestion signal before ack. */ 2659 cc_cong_signal(tp, th, CC_NDUPACK); 2660 cc_ack_received(tp, th, nsegs, 2661 CC_DUPACK); 2662 tcp_timer_activate(tp, TT_REXMT, 0); 2663 tp->t_rtttime = 0; 2664 if (V_tcp_do_prr) { 2665 /* 2666 * snd_ssthresh is already updated by 2667 * cc_cong_signal. 2668 */ 2669 if (tcp_is_sack_recovery(tp, &to)) { 2670 tp->sackhint.prr_delivered = 2671 tp->sackhint.sacked_bytes; 2672 } else { 2673 tp->sackhint.prr_delivered = 2674 imin(tp->snd_max - tp->snd_una, 2675 imin(INT_MAX / 65536, 2676 tp->t_dupacks) * maxseg); 2677 } 2678 tp->sackhint.recover_fs = max(1, 2679 tp->snd_nxt - tp->snd_una); 2680 } 2681 if (tcp_is_sack_recovery(tp, &to)) { 2682 TCPSTAT_INC( 2683 tcps_sack_recovery_episode); 2684 tp->snd_recover = tp->snd_nxt; 2685 tp->snd_cwnd = maxseg; 2686 (void) tcp_output(tp); 2687 if (SEQ_GT(th->th_ack, tp->snd_una)) 2688 goto resume_partialack; 2689 goto drop; 2690 } 2691 tp->snd_nxt = th->th_ack; 2692 tp->snd_cwnd = maxseg; 2693 (void) tcp_output(tp); 2694 KASSERT(tp->snd_limited <= 2, 2695 ("%s: tp->snd_limited too big", 2696 __func__)); 2697 tp->snd_cwnd = tp->snd_ssthresh + 2698 maxseg * 2699 (tp->t_dupacks - tp->snd_limited); 2700 if (SEQ_GT(onxt, tp->snd_nxt)) 2701 tp->snd_nxt = onxt; 2702 goto drop; 2703 } else if (V_tcp_do_rfc3042) { 2704 /* 2705 * Process first and second duplicate 2706 * ACKs. Each indicates a segment 2707 * leaving the network, creating room 2708 * for more. Make sure we can send a 2709 * packet on reception of each duplicate 2710 * ACK by increasing snd_cwnd by one 2711 * segment. Restore the original 2712 * snd_cwnd after packet transmission. 2713 */ 2714 cc_ack_received(tp, th, nsegs, 2715 CC_DUPACK); 2716 uint32_t oldcwnd = tp->snd_cwnd; 2717 tcp_seq oldsndmax = tp->snd_max; 2718 u_int sent; 2719 int avail; 2720 2721 KASSERT(tp->t_dupacks == 1 || 2722 tp->t_dupacks == 2, 2723 ("%s: dupacks not 1 or 2", 2724 __func__)); 2725 if (tp->t_dupacks == 1) 2726 tp->snd_limited = 0; 2727 tp->snd_cwnd = 2728 (tp->snd_nxt - tp->snd_una) + 2729 (tp->t_dupacks - tp->snd_limited) * 2730 maxseg; 2731 /* 2732 * Only call tcp_output when there 2733 * is new data available to be sent 2734 * or we need to send an ACK. 2735 */ 2736 SOCKBUF_LOCK(&so->so_snd); 2737 avail = sbavail(&so->so_snd) - 2738 (tp->snd_nxt - tp->snd_una); 2739 SOCKBUF_UNLOCK(&so->so_snd); 2740 if (avail > 0 || tp->t_flags & TF_ACKNOW) 2741 (void) tcp_output(tp); 2742 sent = tp->snd_max - oldsndmax; 2743 if (sent > maxseg) { 2744 KASSERT((tp->t_dupacks == 2 && 2745 tp->snd_limited == 0) || 2746 (sent == maxseg + 1 && 2747 tp->t_flags & TF_SENTFIN), 2748 ("%s: sent too much", 2749 __func__)); 2750 tp->snd_limited = 2; 2751 } else if (sent > 0) 2752 ++tp->snd_limited; 2753 tp->snd_cwnd = oldcwnd; 2754 goto drop; 2755 } 2756 } 2757 break; 2758 } else { 2759 /* 2760 * This ack is advancing the left edge, reset the 2761 * counter. 2762 */ 2763 tp->t_dupacks = 0; 2764 /* 2765 * If this ack also has new SACK info, increment the 2766 * counter as per rfc6675. The variable 2767 * sack_changed tracks all changes to the SACK 2768 * scoreboard, including when partial ACKs without 2769 * SACK options are received, and clear the scoreboard 2770 * from the left side. Such partial ACKs should not be 2771 * counted as dupacks here. 2772 */ 2773 if (tcp_is_sack_recovery(tp, &to) && 2774 sack_changed) { 2775 tp->t_dupacks++; 2776 /* limit overhead by setting maxseg last */ 2777 if (!IN_FASTRECOVERY(tp->t_flags) && 2778 (tp->sackhint.sacked_bytes > 2779 ((tcprexmtthresh - 1) * 2780 (maxseg = tcp_maxseg(tp))))) { 2781 goto enter_recovery; 2782 } 2783 } 2784 } 2785 2786 resume_partialack: 2787 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2788 ("%s: th_ack <= snd_una", __func__)); 2789 2790 /* 2791 * If the congestion window was inflated to account 2792 * for the other side's cached packets, retract it. 2793 */ 2794 if (IN_FASTRECOVERY(tp->t_flags)) { 2795 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2796 if (tp->t_flags & TF_SACK_PERMIT) 2797 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2798 tcp_timer_activate(tp, TT_REXMT, 0); 2799 tp->t_rtttime = 0; 2800 tcp_do_prr_ack(tp, th, &to); 2801 tp->t_flags |= TF_ACKNOW; 2802 (void) tcp_output(tp); 2803 } else 2804 tcp_sack_partialack(tp, th); 2805 else 2806 tcp_newreno_partial_ack(tp, th); 2807 } else 2808 cc_post_recovery(tp, th); 2809 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2810 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2811 if (V_tcp_do_prr) { 2812 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2813 tp->snd_fack = th->th_ack; 2814 tcp_do_prr_ack(tp, th, &to); 2815 (void) tcp_output(tp); 2816 } 2817 } else 2818 cc_post_recovery(tp, th); 2819 } 2820 /* 2821 * If we reach this point, ACK is not a duplicate, 2822 * i.e., it ACKs something we sent. 2823 */ 2824 if (tp->t_flags & TF_NEEDSYN) { 2825 /* 2826 * T/TCP: Connection was half-synchronized, and our 2827 * SYN has been ACK'd (so connection is now fully 2828 * synchronized). Go to non-starred state, 2829 * increment snd_una for ACK of SYN, and check if 2830 * we can do window scaling. 2831 */ 2832 tp->t_flags &= ~TF_NEEDSYN; 2833 tp->snd_una++; 2834 /* Do window scaling? */ 2835 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2836 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2837 tp->rcv_scale = tp->request_r_scale; 2838 /* Send window already scaled. */ 2839 } 2840 } 2841 2842 process_ACK: 2843 INP_WLOCK_ASSERT(inp); 2844 2845 /* 2846 * Adjust for the SYN bit in sequence space, 2847 * but don't account for it in cwnd calculations. 2848 * This is for the SYN_RECEIVED, non-simultaneous 2849 * SYN case. SYN_SENT and simultaneous SYN are 2850 * treated elsewhere. 2851 */ 2852 if (incforsyn) 2853 tp->snd_una++; 2854 acked = BYTES_THIS_ACK(tp, th); 2855 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2856 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2857 tp->snd_una, th->th_ack, tp, m)); 2858 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2859 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2860 2861 /* 2862 * If we just performed our first retransmit, and the ACK 2863 * arrives within our recovery window, then it was a mistake 2864 * to do the retransmit in the first place. Recover our 2865 * original cwnd and ssthresh, and proceed to transmit where 2866 * we left off. 2867 */ 2868 if (tp->t_rxtshift == 1 && 2869 tp->t_flags & TF_PREVVALID && 2870 tp->t_badrxtwin != 0 && 2871 to.to_flags & TOF_TS && 2872 to.to_tsecr != 0 && 2873 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2874 cc_cong_signal(tp, th, CC_RTO_ERR); 2875 2876 /* 2877 * If we have a timestamp reply, update smoothed 2878 * round trip time. If no timestamp is present but 2879 * transmit timer is running and timed sequence 2880 * number was acked, update smoothed round trip time. 2881 * Since we now have an rtt measurement, cancel the 2882 * timer backoff (cf., Phil Karn's retransmit alg.). 2883 * Recompute the initial retransmit timer. 2884 * 2885 * Some boxes send broken timestamp replies 2886 * during the SYN+ACK phase, ignore 2887 * timestamps of 0 or we could calculate a 2888 * huge RTT and blow up the retransmit timer. 2889 */ 2890 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2891 uint32_t t; 2892 2893 t = tcp_ts_getticks() - to.to_tsecr; 2894 if (!tp->t_rttlow || tp->t_rttlow > t) 2895 tp->t_rttlow = t; 2896 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2897 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2898 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2899 tp->t_rttlow = ticks - tp->t_rtttime; 2900 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2901 } 2902 2903 SOCKBUF_LOCK(&so->so_snd); 2904 /* 2905 * Clear t_acktime if remote side has ACKd all data in the 2906 * socket buffer and FIN (if applicable). 2907 * Otherwise, update t_acktime if we received a sufficiently 2908 * large ACK. 2909 */ 2910 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2911 acked == sbavail(&so->so_snd)) || 2912 acked > sbavail(&so->so_snd)) 2913 tp->t_acktime = 0; 2914 else if (acked > 1) 2915 tp->t_acktime = ticks; 2916 2917 /* 2918 * If all outstanding data is acked, stop retransmit 2919 * timer and remember to restart (more output or persist). 2920 * If there is more data to be acked, restart retransmit 2921 * timer, using current (possibly backed-off) value. 2922 */ 2923 if (th->th_ack == tp->snd_max) { 2924 tcp_timer_activate(tp, TT_REXMT, 0); 2925 needoutput = 1; 2926 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2927 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2928 2929 /* 2930 * If no data (only SYN) was ACK'd, 2931 * skip rest of ACK processing. 2932 */ 2933 if (acked == 0) { 2934 SOCKBUF_UNLOCK(&so->so_snd); 2935 goto step6; 2936 } 2937 2938 /* 2939 * Let the congestion control algorithm update congestion 2940 * control related information. This typically means increasing 2941 * the congestion window. 2942 */ 2943 cc_ack_received(tp, th, nsegs, CC_ACK); 2944 2945 if (acked > sbavail(&so->so_snd)) { 2946 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2947 tp->snd_wnd -= sbavail(&so->so_snd); 2948 else 2949 tp->snd_wnd = 0; 2950 mfree = sbcut_locked(&so->so_snd, 2951 (int)sbavail(&so->so_snd)); 2952 ourfinisacked = 1; 2953 } else { 2954 mfree = sbcut_locked(&so->so_snd, acked); 2955 if (tp->snd_wnd >= (uint32_t) acked) 2956 tp->snd_wnd -= acked; 2957 else 2958 tp->snd_wnd = 0; 2959 ourfinisacked = 0; 2960 } 2961 /* NB: sowwakeup_locked() does an implicit unlock. */ 2962 sowwakeup_locked(so); 2963 m_freem(mfree); 2964 /* Detect una wraparound. */ 2965 if (!IN_RECOVERY(tp->t_flags) && 2966 SEQ_GT(tp->snd_una, tp->snd_recover) && 2967 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2968 tp->snd_recover = th->th_ack - 1; 2969 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2970 if (IN_RECOVERY(tp->t_flags) && 2971 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2972 EXIT_RECOVERY(tp->t_flags); 2973 } 2974 tp->snd_una = th->th_ack; 2975 if (tp->t_flags & TF_SACK_PERMIT) { 2976 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2977 tp->snd_recover = tp->snd_una; 2978 } 2979 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2980 tp->snd_nxt = tp->snd_una; 2981 2982 switch (tp->t_state) { 2983 /* 2984 * In FIN_WAIT_1 STATE in addition to the processing 2985 * for the ESTABLISHED state if our FIN is now acknowledged 2986 * then enter FIN_WAIT_2. 2987 */ 2988 case TCPS_FIN_WAIT_1: 2989 if (ourfinisacked) { 2990 /* 2991 * If we can't receive any more 2992 * data, then closing user can proceed. 2993 * Starting the timer is contrary to the 2994 * specification, but if we don't get a FIN 2995 * we'll hang forever. 2996 */ 2997 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 2998 soisdisconnected(so); 2999 tcp_timer_activate(tp, TT_2MSL, 3000 (tcp_fast_finwait2_recycle ? 3001 tcp_finwait2_timeout : 3002 TP_MAXIDLE(tp))); 3003 } 3004 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3005 } 3006 break; 3007 3008 /* 3009 * In CLOSING STATE in addition to the processing for 3010 * the ESTABLISHED state if the ACK acknowledges our FIN 3011 * then enter the TIME-WAIT state, otherwise ignore 3012 * the segment. 3013 */ 3014 case TCPS_CLOSING: 3015 if (ourfinisacked) { 3016 tcp_twstart(tp); 3017 m_freem(m); 3018 return; 3019 } 3020 break; 3021 3022 /* 3023 * In LAST_ACK, we may still be waiting for data to drain 3024 * and/or to be acked, as well as for the ack of our FIN. 3025 * If our FIN is now acknowledged, delete the TCB, 3026 * enter the closed state and return. 3027 */ 3028 case TCPS_LAST_ACK: 3029 if (ourfinisacked) { 3030 tp = tcp_close(tp); 3031 goto drop; 3032 } 3033 break; 3034 } 3035 } 3036 3037 step6: 3038 INP_WLOCK_ASSERT(inp); 3039 3040 /* 3041 * Update window information. 3042 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3043 */ 3044 if ((thflags & TH_ACK) && 3045 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3046 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3047 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3048 /* keep track of pure window updates */ 3049 if (tlen == 0 && 3050 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3051 TCPSTAT_INC(tcps_rcvwinupd); 3052 tp->snd_wnd = tiwin; 3053 tp->snd_wl1 = th->th_seq; 3054 tp->snd_wl2 = th->th_ack; 3055 if (tp->snd_wnd > tp->max_sndwnd) 3056 tp->max_sndwnd = tp->snd_wnd; 3057 needoutput = 1; 3058 } 3059 3060 /* 3061 * Process segments with URG. 3062 */ 3063 if ((thflags & TH_URG) && th->th_urp && 3064 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3065 /* 3066 * This is a kludge, but if we receive and accept 3067 * random urgent pointers, we'll crash in 3068 * soreceive. It's hard to imagine someone 3069 * actually wanting to send this much urgent data. 3070 */ 3071 SOCKBUF_LOCK(&so->so_rcv); 3072 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3073 th->th_urp = 0; /* XXX */ 3074 thflags &= ~TH_URG; /* XXX */ 3075 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3076 goto dodata; /* XXX */ 3077 } 3078 /* 3079 * If this segment advances the known urgent pointer, 3080 * then mark the data stream. This should not happen 3081 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3082 * a FIN has been received from the remote side. 3083 * In these states we ignore the URG. 3084 * 3085 * According to RFC961 (Assigned Protocols), 3086 * the urgent pointer points to the last octet 3087 * of urgent data. We continue, however, 3088 * to consider it to indicate the first octet 3089 * of data past the urgent section as the original 3090 * spec states (in one of two places). 3091 */ 3092 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3093 tp->rcv_up = th->th_seq + th->th_urp; 3094 so->so_oobmark = sbavail(&so->so_rcv) + 3095 (tp->rcv_up - tp->rcv_nxt) - 1; 3096 if (so->so_oobmark == 0) 3097 so->so_rcv.sb_state |= SBS_RCVATMARK; 3098 sohasoutofband(so); 3099 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3100 } 3101 SOCKBUF_UNLOCK(&so->so_rcv); 3102 /* 3103 * Remove out of band data so doesn't get presented to user. 3104 * This can happen independent of advancing the URG pointer, 3105 * but if two URG's are pending at once, some out-of-band 3106 * data may creep in... ick. 3107 */ 3108 if (th->th_urp <= (uint32_t)tlen && 3109 !(so->so_options & SO_OOBINLINE)) { 3110 /* hdr drop is delayed */ 3111 tcp_pulloutofband(so, th, m, drop_hdrlen); 3112 } 3113 } else { 3114 /* 3115 * If no out of band data is expected, 3116 * pull receive urgent pointer along 3117 * with the receive window. 3118 */ 3119 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3120 tp->rcv_up = tp->rcv_nxt; 3121 } 3122 dodata: /* XXX */ 3123 INP_WLOCK_ASSERT(inp); 3124 3125 /* 3126 * Process the segment text, merging it into the TCP sequencing queue, 3127 * and arranging for acknowledgment of receipt if necessary. 3128 * This process logically involves adjusting tp->rcv_wnd as data 3129 * is presented to the user (this happens in tcp_usrreq.c, 3130 * case PRU_RCVD). If a FIN has already been received on this 3131 * connection then we just ignore the text. 3132 */ 3133 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3134 IS_FASTOPEN(tp->t_flags)); 3135 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3136 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3137 tcp_seq save_start = th->th_seq; 3138 tcp_seq save_rnxt = tp->rcv_nxt; 3139 int save_tlen = tlen; 3140 m_adj(m, drop_hdrlen); /* delayed header drop */ 3141 /* 3142 * Insert segment which includes th into TCP reassembly queue 3143 * with control block tp. Set thflags to whether reassembly now 3144 * includes a segment with FIN. This handles the common case 3145 * inline (segment is the next to be received on an established 3146 * connection, and the queue is empty), avoiding linkage into 3147 * and removal from the queue and repetition of various 3148 * conversions. 3149 * Set DELACK for segments received in order, but ack 3150 * immediately when segments are out of order (so 3151 * fast retransmit can work). 3152 */ 3153 if (th->th_seq == tp->rcv_nxt && 3154 SEGQ_EMPTY(tp) && 3155 (TCPS_HAVEESTABLISHED(tp->t_state) || 3156 tfo_syn)) { 3157 if (DELAY_ACK(tp, tlen) || tfo_syn) 3158 tp->t_flags |= TF_DELACK; 3159 else 3160 tp->t_flags |= TF_ACKNOW; 3161 tp->rcv_nxt += tlen; 3162 if (tlen && 3163 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3164 (tp->t_fbyte_in == 0)) { 3165 tp->t_fbyte_in = ticks; 3166 if (tp->t_fbyte_in == 0) 3167 tp->t_fbyte_in = 1; 3168 if (tp->t_fbyte_out && tp->t_fbyte_in) 3169 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3170 } 3171 thflags = tcp_get_flags(th) & TH_FIN; 3172 TCPSTAT_INC(tcps_rcvpack); 3173 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3174 SOCKBUF_LOCK(&so->so_rcv); 3175 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3176 m_freem(m); 3177 else 3178 sbappendstream_locked(&so->so_rcv, m, 0); 3179 tp->t_flags |= TF_WAKESOR; 3180 } else { 3181 /* 3182 * XXX: Due to the header drop above "th" is 3183 * theoretically invalid by now. Fortunately 3184 * m_adj() doesn't actually frees any mbufs 3185 * when trimming from the head. 3186 */ 3187 tcp_seq temp = save_start; 3188 3189 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3190 tp->t_flags |= TF_ACKNOW; 3191 } 3192 if ((tp->t_flags & TF_SACK_PERMIT) && 3193 (save_tlen > 0) && 3194 TCPS_HAVEESTABLISHED(tp->t_state)) { 3195 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3196 /* 3197 * DSACK actually handled in the fastpath 3198 * above. 3199 */ 3200 tcp_update_sack_list(tp, save_start, 3201 save_start + save_tlen); 3202 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3203 if ((tp->rcv_numsacks >= 1) && 3204 (tp->sackblks[0].end == save_start)) { 3205 /* 3206 * Partial overlap, recorded at todrop 3207 * above. 3208 */ 3209 tcp_update_sack_list(tp, 3210 tp->sackblks[0].start, 3211 tp->sackblks[0].end); 3212 } else { 3213 tcp_update_dsack_list(tp, save_start, 3214 save_start + save_tlen); 3215 } 3216 } else if (tlen >= save_tlen) { 3217 /* Update of sackblks. */ 3218 tcp_update_dsack_list(tp, save_start, 3219 save_start + save_tlen); 3220 } else if (tlen > 0) { 3221 tcp_update_dsack_list(tp, save_start, 3222 save_start + tlen); 3223 } 3224 } 3225 tcp_handle_wakeup(tp); 3226 #if 0 3227 /* 3228 * Note the amount of data that peer has sent into 3229 * our window, in order to estimate the sender's 3230 * buffer size. 3231 * XXX: Unused. 3232 */ 3233 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3234 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3235 else 3236 len = so->so_rcv.sb_hiwat; 3237 #endif 3238 } else { 3239 m_freem(m); 3240 thflags &= ~TH_FIN; 3241 } 3242 3243 /* 3244 * If FIN is received ACK the FIN and let the user know 3245 * that the connection is closing. 3246 */ 3247 if (thflags & TH_FIN) { 3248 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3249 /* The socket upcall is handled by socantrcvmore. */ 3250 socantrcvmore(so); 3251 /* 3252 * If connection is half-synchronized 3253 * (ie NEEDSYN flag on) then delay ACK, 3254 * so it may be piggybacked when SYN is sent. 3255 * Otherwise, since we received a FIN then no 3256 * more input can be expected, send ACK now. 3257 */ 3258 if (tp->t_flags & TF_NEEDSYN) 3259 tp->t_flags |= TF_DELACK; 3260 else 3261 tp->t_flags |= TF_ACKNOW; 3262 tp->rcv_nxt++; 3263 } 3264 switch (tp->t_state) { 3265 /* 3266 * In SYN_RECEIVED and ESTABLISHED STATES 3267 * enter the CLOSE_WAIT state. 3268 */ 3269 case TCPS_SYN_RECEIVED: 3270 tp->t_starttime = ticks; 3271 /* FALLTHROUGH */ 3272 case TCPS_ESTABLISHED: 3273 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3274 break; 3275 3276 /* 3277 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3278 * enter the CLOSING state. 3279 */ 3280 case TCPS_FIN_WAIT_1: 3281 tcp_state_change(tp, TCPS_CLOSING); 3282 break; 3283 3284 /* 3285 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3286 * starting the time-wait timer, turning off the other 3287 * standard timers. 3288 */ 3289 case TCPS_FIN_WAIT_2: 3290 tcp_twstart(tp); 3291 return; 3292 } 3293 } 3294 TCP_PROBE3(debug__input, tp, th, m); 3295 3296 /* 3297 * Return any desired output. 3298 */ 3299 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3300 (void) tcp_output(tp); 3301 3302 check_delack: 3303 INP_WLOCK_ASSERT(inp); 3304 3305 if (tp->t_flags & TF_DELACK) { 3306 tp->t_flags &= ~TF_DELACK; 3307 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3308 } 3309 INP_WUNLOCK(inp); 3310 return; 3311 3312 dropafterack: 3313 /* 3314 * Generate an ACK dropping incoming segment if it occupies 3315 * sequence space, where the ACK reflects our state. 3316 * 3317 * We can now skip the test for the RST flag since all 3318 * paths to this code happen after packets containing 3319 * RST have been dropped. 3320 * 3321 * In the SYN-RECEIVED state, don't send an ACK unless the 3322 * segment we received passes the SYN-RECEIVED ACK test. 3323 * If it fails send a RST. This breaks the loop in the 3324 * "LAND" DoS attack, and also prevents an ACK storm 3325 * between two listening ports that have been sent forged 3326 * SYN segments, each with the source address of the other. 3327 */ 3328 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3329 (SEQ_GT(tp->snd_una, th->th_ack) || 3330 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3331 rstreason = BANDLIM_RST_OPENPORT; 3332 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3333 goto dropwithreset; 3334 } 3335 TCP_PROBE3(debug__input, tp, th, m); 3336 tp->t_flags |= TF_ACKNOW; 3337 (void) tcp_output(tp); 3338 INP_WUNLOCK(inp); 3339 m_freem(m); 3340 return; 3341 3342 dropwithreset: 3343 if (tp != NULL) { 3344 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3345 INP_WUNLOCK(inp); 3346 } else 3347 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3348 return; 3349 3350 drop: 3351 /* 3352 * Drop space held by incoming segment and return. 3353 */ 3354 TCP_PROBE3(debug__input, tp, th, m); 3355 if (tp != NULL) { 3356 INP_WUNLOCK(inp); 3357 } 3358 m_freem(m); 3359 } 3360 3361 /* 3362 * Issue RST and make ACK acceptable to originator of segment. 3363 * The mbuf must still include the original packet header. 3364 * tp may be NULL. 3365 */ 3366 void 3367 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3368 int tlen, int rstreason) 3369 { 3370 #ifdef INET 3371 struct ip *ip; 3372 #endif 3373 #ifdef INET6 3374 struct ip6_hdr *ip6; 3375 #endif 3376 3377 if (tp != NULL) { 3378 INP_LOCK_ASSERT(tptoinpcb(tp)); 3379 } 3380 3381 /* Don't bother if destination was broadcast/multicast. */ 3382 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3383 goto drop; 3384 #ifdef INET6 3385 if (mtod(m, struct ip *)->ip_v == 6) { 3386 ip6 = mtod(m, struct ip6_hdr *); 3387 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3388 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3389 goto drop; 3390 /* IPv6 anycast check is done at tcp6_input() */ 3391 } 3392 #endif 3393 #if defined(INET) && defined(INET6) 3394 else 3395 #endif 3396 #ifdef INET 3397 { 3398 ip = mtod(m, struct ip *); 3399 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3400 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3401 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3402 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3403 goto drop; 3404 } 3405 #endif 3406 3407 /* Perform bandwidth limiting. */ 3408 if (badport_bandlim(rstreason) < 0) 3409 goto drop; 3410 3411 /* tcp_respond consumes the mbuf chain. */ 3412 if (tcp_get_flags(th) & TH_ACK) { 3413 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3414 th->th_ack, TH_RST); 3415 } else { 3416 if (tcp_get_flags(th) & TH_SYN) 3417 tlen++; 3418 if (tcp_get_flags(th) & TH_FIN) 3419 tlen++; 3420 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3421 (tcp_seq)0, TH_RST|TH_ACK); 3422 } 3423 return; 3424 drop: 3425 m_freem(m); 3426 } 3427 3428 /* 3429 * Parse TCP options and place in tcpopt. 3430 */ 3431 void 3432 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3433 { 3434 int opt, optlen; 3435 3436 to->to_flags = 0; 3437 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3438 opt = cp[0]; 3439 if (opt == TCPOPT_EOL) 3440 break; 3441 if (opt == TCPOPT_NOP) 3442 optlen = 1; 3443 else { 3444 if (cnt < 2) 3445 break; 3446 optlen = cp[1]; 3447 if (optlen < 2 || optlen > cnt) 3448 break; 3449 } 3450 switch (opt) { 3451 case TCPOPT_MAXSEG: 3452 if (optlen != TCPOLEN_MAXSEG) 3453 continue; 3454 if (!(flags & TO_SYN)) 3455 continue; 3456 to->to_flags |= TOF_MSS; 3457 bcopy((char *)cp + 2, 3458 (char *)&to->to_mss, sizeof(to->to_mss)); 3459 to->to_mss = ntohs(to->to_mss); 3460 break; 3461 case TCPOPT_WINDOW: 3462 if (optlen != TCPOLEN_WINDOW) 3463 continue; 3464 if (!(flags & TO_SYN)) 3465 continue; 3466 to->to_flags |= TOF_SCALE; 3467 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3468 break; 3469 case TCPOPT_TIMESTAMP: 3470 if (optlen != TCPOLEN_TIMESTAMP) 3471 continue; 3472 to->to_flags |= TOF_TS; 3473 bcopy((char *)cp + 2, 3474 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3475 to->to_tsval = ntohl(to->to_tsval); 3476 bcopy((char *)cp + 6, 3477 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3478 to->to_tsecr = ntohl(to->to_tsecr); 3479 break; 3480 case TCPOPT_SIGNATURE: 3481 /* 3482 * In order to reply to a host which has set the 3483 * TCP_SIGNATURE option in its initial SYN, we have 3484 * to record the fact that the option was observed 3485 * here for the syncache code to perform the correct 3486 * response. 3487 */ 3488 if (optlen != TCPOLEN_SIGNATURE) 3489 continue; 3490 to->to_flags |= TOF_SIGNATURE; 3491 to->to_signature = cp + 2; 3492 break; 3493 case TCPOPT_SACK_PERMITTED: 3494 if (optlen != TCPOLEN_SACK_PERMITTED) 3495 continue; 3496 if (!(flags & TO_SYN)) 3497 continue; 3498 if (!V_tcp_do_sack) 3499 continue; 3500 to->to_flags |= TOF_SACKPERM; 3501 break; 3502 case TCPOPT_SACK: 3503 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3504 continue; 3505 if (flags & TO_SYN) 3506 continue; 3507 to->to_flags |= TOF_SACK; 3508 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3509 to->to_sacks = cp + 2; 3510 TCPSTAT_INC(tcps_sack_rcv_blocks); 3511 break; 3512 case TCPOPT_FAST_OPEN: 3513 /* 3514 * Cookie length validation is performed by the 3515 * server side cookie checking code or the client 3516 * side cookie cache update code. 3517 */ 3518 if (!(flags & TO_SYN)) 3519 continue; 3520 if (!V_tcp_fastopen_client_enable && 3521 !V_tcp_fastopen_server_enable) 3522 continue; 3523 to->to_flags |= TOF_FASTOPEN; 3524 to->to_tfo_len = optlen - 2; 3525 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3526 break; 3527 default: 3528 continue; 3529 } 3530 } 3531 } 3532 3533 /* 3534 * Pull out of band byte out of a segment so 3535 * it doesn't appear in the user's data queue. 3536 * It is still reflected in the segment length for 3537 * sequencing purposes. 3538 */ 3539 void 3540 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3541 int off) 3542 { 3543 int cnt = off + th->th_urp - 1; 3544 3545 while (cnt >= 0) { 3546 if (m->m_len > cnt) { 3547 char *cp = mtod(m, caddr_t) + cnt; 3548 struct tcpcb *tp = sototcpcb(so); 3549 3550 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3551 3552 tp->t_iobc = *cp; 3553 tp->t_oobflags |= TCPOOB_HAVEDATA; 3554 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3555 m->m_len--; 3556 if (m->m_flags & M_PKTHDR) 3557 m->m_pkthdr.len--; 3558 return; 3559 } 3560 cnt -= m->m_len; 3561 m = m->m_next; 3562 if (m == NULL) 3563 break; 3564 } 3565 panic("tcp_pulloutofband"); 3566 } 3567 3568 /* 3569 * Collect new round-trip time estimate 3570 * and update averages and current timeout. 3571 */ 3572 void 3573 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3574 { 3575 int delta; 3576 3577 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3578 3579 TCPSTAT_INC(tcps_rttupdated); 3580 if (tp->t_rttupdated < UCHAR_MAX) 3581 tp->t_rttupdated++; 3582 #ifdef STATS 3583 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3584 imax(0, rtt * 1000 / hz)); 3585 #endif 3586 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3587 /* 3588 * srtt is stored as fixed point with 5 bits after the 3589 * binary point (i.e., scaled by 8). The following magic 3590 * is equivalent to the smoothing algorithm in rfc793 with 3591 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3592 * point). Adjust rtt to origin 0. 3593 */ 3594 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3595 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3596 3597 if ((tp->t_srtt += delta) <= 0) 3598 tp->t_srtt = 1; 3599 3600 /* 3601 * We accumulate a smoothed rtt variance (actually, a 3602 * smoothed mean difference), then set the retransmit 3603 * timer to smoothed rtt + 4 times the smoothed variance. 3604 * rttvar is stored as fixed point with 4 bits after the 3605 * binary point (scaled by 16). The following is 3606 * equivalent to rfc793 smoothing with an alpha of .75 3607 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3608 * rfc793's wired-in beta. 3609 */ 3610 if (delta < 0) 3611 delta = -delta; 3612 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3613 if ((tp->t_rttvar += delta) <= 0) 3614 tp->t_rttvar = 1; 3615 } else { 3616 /* 3617 * No rtt measurement yet - use the unsmoothed rtt. 3618 * Set the variance to half the rtt (so our first 3619 * retransmit happens at 3*rtt). 3620 */ 3621 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3622 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3623 } 3624 tp->t_rtttime = 0; 3625 tp->t_rxtshift = 0; 3626 3627 /* 3628 * the retransmit should happen at rtt + 4 * rttvar. 3629 * Because of the way we do the smoothing, srtt and rttvar 3630 * will each average +1/2 tick of bias. When we compute 3631 * the retransmit timer, we want 1/2 tick of rounding and 3632 * 1 extra tick because of +-1/2 tick uncertainty in the 3633 * firing of the timer. The bias will give us exactly the 3634 * 1.5 tick we need. But, because the bias is 3635 * statistical, we have to test that we don't drop below 3636 * the minimum feasible timer (which is 2 ticks). 3637 */ 3638 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3639 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3640 3641 /* 3642 * We received an ack for a packet that wasn't retransmitted; 3643 * it is probably safe to discard any error indications we've 3644 * received recently. This isn't quite right, but close enough 3645 * for now (a route might have failed after we sent a segment, 3646 * and the return path might not be symmetrical). 3647 */ 3648 tp->t_softerror = 0; 3649 } 3650 3651 /* 3652 * Determine a reasonable value for maxseg size. 3653 * If the route is known, check route for mtu. 3654 * If none, use an mss that can be handled on the outgoing interface 3655 * without forcing IP to fragment. If no route is found, route has no mtu, 3656 * or the destination isn't local, use a default, hopefully conservative 3657 * size (usually 512 or the default IP max size, but no more than the mtu 3658 * of the interface), as we can't discover anything about intervening 3659 * gateways or networks. We also initialize the congestion/slow start 3660 * window to be a single segment if the destination isn't local. 3661 * While looking at the routing entry, we also initialize other path-dependent 3662 * parameters from pre-set or cached values in the routing entry. 3663 * 3664 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3665 * IP options, e.g. IPSEC data, since length of this data may vary, and 3666 * thus it is calculated for every segment separately in tcp_output(). 3667 * 3668 * NOTE that this routine is only called when we process an incoming 3669 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3670 * settings are handled in tcp_mssopt(). 3671 */ 3672 void 3673 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3674 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3675 { 3676 int mss = 0; 3677 uint32_t maxmtu = 0; 3678 struct inpcb *inp = tptoinpcb(tp); 3679 struct hc_metrics_lite metrics; 3680 #ifdef INET6 3681 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3682 size_t min_protoh = isipv6 ? 3683 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3684 sizeof (struct tcpiphdr); 3685 #else 3686 size_t min_protoh = sizeof(struct tcpiphdr); 3687 #endif 3688 3689 INP_WLOCK_ASSERT(inp); 3690 3691 if (tp->t_port) 3692 min_protoh += V_tcp_udp_tunneling_overhead; 3693 if (mtuoffer != -1) { 3694 KASSERT(offer == -1, ("%s: conflict", __func__)); 3695 offer = mtuoffer - min_protoh; 3696 } 3697 3698 /* Initialize. */ 3699 #ifdef INET6 3700 if (isipv6) { 3701 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3702 tp->t_maxseg = V_tcp_v6mssdflt; 3703 } 3704 #endif 3705 #if defined(INET) && defined(INET6) 3706 else 3707 #endif 3708 #ifdef INET 3709 { 3710 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3711 tp->t_maxseg = V_tcp_mssdflt; 3712 } 3713 #endif 3714 3715 /* 3716 * No route to sender, stay with default mss and return. 3717 */ 3718 if (maxmtu == 0) { 3719 /* 3720 * In case we return early we need to initialize metrics 3721 * to a defined state as tcp_hc_get() would do for us 3722 * if there was no cache hit. 3723 */ 3724 if (metricptr != NULL) 3725 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3726 return; 3727 } 3728 3729 /* What have we got? */ 3730 switch (offer) { 3731 case 0: 3732 /* 3733 * Offer == 0 means that there was no MSS on the SYN 3734 * segment, in this case we use tcp_mssdflt as 3735 * already assigned to t_maxseg above. 3736 */ 3737 offer = tp->t_maxseg; 3738 break; 3739 3740 case -1: 3741 /* 3742 * Offer == -1 means that we didn't receive SYN yet. 3743 */ 3744 /* FALLTHROUGH */ 3745 3746 default: 3747 /* 3748 * Prevent DoS attack with too small MSS. Round up 3749 * to at least minmss. 3750 */ 3751 offer = max(offer, V_tcp_minmss); 3752 } 3753 3754 /* 3755 * rmx information is now retrieved from tcp_hostcache. 3756 */ 3757 tcp_hc_get(&inp->inp_inc, &metrics); 3758 if (metricptr != NULL) 3759 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3760 3761 /* 3762 * If there's a discovered mtu in tcp hostcache, use it. 3763 * Else, use the link mtu. 3764 */ 3765 if (metrics.rmx_mtu) 3766 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3767 else { 3768 #ifdef INET6 3769 if (isipv6) { 3770 mss = maxmtu - min_protoh; 3771 if (!V_path_mtu_discovery && 3772 !in6_localaddr(&inp->in6p_faddr)) 3773 mss = min(mss, V_tcp_v6mssdflt); 3774 } 3775 #endif 3776 #if defined(INET) && defined(INET6) 3777 else 3778 #endif 3779 #ifdef INET 3780 { 3781 mss = maxmtu - min_protoh; 3782 if (!V_path_mtu_discovery && 3783 !in_localaddr(inp->inp_faddr)) 3784 mss = min(mss, V_tcp_mssdflt); 3785 } 3786 #endif 3787 /* 3788 * XXX - The above conditional (mss = maxmtu - min_protoh) 3789 * probably violates the TCP spec. 3790 * The problem is that, since we don't know the 3791 * other end's MSS, we are supposed to use a conservative 3792 * default. But, if we do that, then MTU discovery will 3793 * never actually take place, because the conservative 3794 * default is much less than the MTUs typically seen 3795 * on the Internet today. For the moment, we'll sweep 3796 * this under the carpet. 3797 * 3798 * The conservative default might not actually be a problem 3799 * if the only case this occurs is when sending an initial 3800 * SYN with options and data to a host we've never talked 3801 * to before. Then, they will reply with an MSS value which 3802 * will get recorded and the new parameters should get 3803 * recomputed. For Further Study. 3804 */ 3805 } 3806 mss = min(mss, offer); 3807 3808 /* 3809 * Sanity check: make sure that maxseg will be large 3810 * enough to allow some data on segments even if the 3811 * all the option space is used (40bytes). Otherwise 3812 * funny things may happen in tcp_output. 3813 * 3814 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3815 */ 3816 mss = max(mss, 64); 3817 3818 tp->t_maxseg = mss; 3819 } 3820 3821 void 3822 tcp_mss(struct tcpcb *tp, int offer) 3823 { 3824 int mss; 3825 uint32_t bufsize; 3826 struct inpcb *inp = tptoinpcb(tp); 3827 struct socket *so; 3828 struct hc_metrics_lite metrics; 3829 struct tcp_ifcap cap; 3830 3831 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3832 3833 bzero(&cap, sizeof(cap)); 3834 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3835 3836 mss = tp->t_maxseg; 3837 3838 /* 3839 * If there's a pipesize, change the socket buffer to that size, 3840 * don't change if sb_hiwat is different than default (then it 3841 * has been changed on purpose with setsockopt). 3842 * Make the socket buffers an integral number of mss units; 3843 * if the mss is larger than the socket buffer, decrease the mss. 3844 */ 3845 so = inp->inp_socket; 3846 SOCKBUF_LOCK(&so->so_snd); 3847 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3848 bufsize = metrics.rmx_sendpipe; 3849 else 3850 bufsize = so->so_snd.sb_hiwat; 3851 if (bufsize < mss) 3852 mss = bufsize; 3853 else { 3854 bufsize = roundup(bufsize, mss); 3855 if (bufsize > sb_max) 3856 bufsize = sb_max; 3857 if (bufsize > so->so_snd.sb_hiwat) 3858 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3859 } 3860 SOCKBUF_UNLOCK(&so->so_snd); 3861 /* 3862 * Sanity check: make sure that maxseg will be large 3863 * enough to allow some data on segments even if the 3864 * all the option space is used (40bytes). Otherwise 3865 * funny things may happen in tcp_output. 3866 * 3867 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3868 */ 3869 tp->t_maxseg = max(mss, 64); 3870 3871 SOCKBUF_LOCK(&so->so_rcv); 3872 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3873 bufsize = metrics.rmx_recvpipe; 3874 else 3875 bufsize = so->so_rcv.sb_hiwat; 3876 if (bufsize > mss) { 3877 bufsize = roundup(bufsize, mss); 3878 if (bufsize > sb_max) 3879 bufsize = sb_max; 3880 if (bufsize > so->so_rcv.sb_hiwat) 3881 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3882 } 3883 SOCKBUF_UNLOCK(&so->so_rcv); 3884 3885 /* Check the interface for TSO capabilities. */ 3886 if (cap.ifcap & CSUM_TSO) { 3887 tp->t_flags |= TF_TSO; 3888 tp->t_tsomax = cap.tsomax; 3889 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3890 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3891 } 3892 } 3893 3894 /* 3895 * Determine the MSS option to send on an outgoing SYN. 3896 */ 3897 int 3898 tcp_mssopt(struct in_conninfo *inc) 3899 { 3900 int mss = 0; 3901 uint32_t thcmtu = 0; 3902 uint32_t maxmtu = 0; 3903 size_t min_protoh; 3904 3905 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3906 3907 #ifdef INET6 3908 if (inc->inc_flags & INC_ISIPV6) { 3909 mss = V_tcp_v6mssdflt; 3910 maxmtu = tcp_maxmtu6(inc, NULL); 3911 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3912 } 3913 #endif 3914 #if defined(INET) && defined(INET6) 3915 else 3916 #endif 3917 #ifdef INET 3918 { 3919 mss = V_tcp_mssdflt; 3920 maxmtu = tcp_maxmtu(inc, NULL); 3921 min_protoh = sizeof(struct tcpiphdr); 3922 } 3923 #endif 3924 #if defined(INET6) || defined(INET) 3925 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3926 #endif 3927 3928 if (maxmtu && thcmtu) 3929 mss = min(maxmtu, thcmtu) - min_protoh; 3930 else if (maxmtu || thcmtu) 3931 mss = max(maxmtu, thcmtu) - min_protoh; 3932 3933 return (mss); 3934 } 3935 3936 void 3937 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 3938 { 3939 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3940 int maxseg = tcp_maxseg(tp); 3941 3942 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3943 3944 /* 3945 * Compute the amount of data that this ACK is indicating 3946 * (del_data) and an estimate of how many bytes are in the 3947 * network. 3948 */ 3949 if (tcp_is_sack_recovery(tp, to) || 3950 (IN_CONGRECOVERY(tp->t_flags) && 3951 !IN_FASTRECOVERY(tp->t_flags))) { 3952 del_data = tp->sackhint.delivered_data; 3953 if (V_tcp_do_newsack) 3954 pipe = tcp_compute_pipe(tp); 3955 else 3956 pipe = (tp->snd_nxt - tp->snd_fack) + 3957 tp->sackhint.sack_bytes_rexmit; 3958 } else { 3959 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 3960 tp->snd_recover - tp->snd_una)) 3961 del_data = maxseg; 3962 pipe = imax(0, tp->snd_max - tp->snd_una - 3963 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 3964 } 3965 tp->sackhint.prr_delivered += del_data; 3966 /* 3967 * Proportional Rate Reduction 3968 */ 3969 if (pipe >= tp->snd_ssthresh) { 3970 if (tp->sackhint.recover_fs == 0) 3971 tp->sackhint.recover_fs = 3972 imax(1, tp->snd_nxt - tp->snd_una); 3973 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 3974 tp->snd_ssthresh, tp->sackhint.recover_fs) - 3975 tp->sackhint.prr_out; 3976 } else { 3977 if (V_tcp_do_prr_conservative || (del_data == 0)) 3978 limit = tp->sackhint.prr_delivered - 3979 tp->sackhint.prr_out; 3980 else 3981 limit = imax(tp->sackhint.prr_delivered - 3982 tp->sackhint.prr_out, del_data) + 3983 maxseg; 3984 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 3985 } 3986 snd_cnt = imax(snd_cnt, 0) / maxseg; 3987 /* 3988 * Send snd_cnt new data into the network in response to this ack. 3989 * If there is going to be a SACK retransmission, adjust snd_cwnd 3990 * accordingly. 3991 */ 3992 if (IN_FASTRECOVERY(tp->t_flags)) { 3993 if (tcp_is_sack_recovery(tp, to)) { 3994 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 3995 tp->sackhint.sack_bytes_rexmit + 3996 (snd_cnt * maxseg); 3997 } else { 3998 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 3999 (snd_cnt * maxseg); 4000 } 4001 } else if (IN_CONGRECOVERY(tp->t_flags)) 4002 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4003 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4004 } 4005 4006 /* 4007 * On a partial ack arrives, force the retransmission of the 4008 * next unacknowledged segment. Do not clear tp->t_dupacks. 4009 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4010 * be started again. 4011 */ 4012 void 4013 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4014 { 4015 tcp_seq onxt = tp->snd_nxt; 4016 uint32_t ocwnd = tp->snd_cwnd; 4017 u_int maxseg = tcp_maxseg(tp); 4018 4019 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4020 4021 tcp_timer_activate(tp, TT_REXMT, 0); 4022 tp->t_rtttime = 0; 4023 tp->snd_nxt = th->th_ack; 4024 /* 4025 * Set snd_cwnd to one segment beyond acknowledged offset. 4026 * (tp->snd_una has not yet been updated when this function is called.) 4027 */ 4028 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4029 tp->t_flags |= TF_ACKNOW; 4030 (void) tcp_output(tp); 4031 tp->snd_cwnd = ocwnd; 4032 if (SEQ_GT(onxt, tp->snd_nxt)) 4033 tp->snd_nxt = onxt; 4034 /* 4035 * Partial window deflation. Relies on fact that tp->snd_una 4036 * not updated yet. 4037 */ 4038 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4039 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4040 else 4041 tp->snd_cwnd = 0; 4042 tp->snd_cwnd += maxseg; 4043 } 4044 4045 int 4046 tcp_compute_pipe(struct tcpcb *tp) 4047 { 4048 if (tp->t_fb->tfb_compute_pipe == NULL) { 4049 return (tp->snd_max - tp->snd_una + 4050 tp->sackhint.sack_bytes_rexmit - 4051 tp->sackhint.sacked_bytes); 4052 } else { 4053 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4054 } 4055 } 4056 4057 uint32_t 4058 tcp_compute_initwnd(uint32_t maxseg) 4059 { 4060 /* 4061 * Calculate the Initial Window, also used as Restart Window 4062 * 4063 * RFC5681 Section 3.1 specifies the default conservative values. 4064 * RFC3390 specifies slightly more aggressive values. 4065 * RFC6928 increases it to ten segments. 4066 * Support for user specified value for initial flight size. 4067 */ 4068 if (V_tcp_initcwnd_segments) 4069 return min(V_tcp_initcwnd_segments * maxseg, 4070 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4071 else if (V_tcp_do_rfc3390) 4072 return min(4 * maxseg, max(2 * maxseg, 4380)); 4073 else { 4074 /* Per RFC5681 Section 3.1 */ 4075 if (maxseg > 2190) 4076 return (2 * maxseg); 4077 else if (maxseg > 1095) 4078 return (3 * maxseg); 4079 else 4080 return (4 * maxseg); 4081 } 4082 } 4083